andrewmt

• Teale, Andrew Michael; Huynh, Bang C.; Helgaker, Trygve & Tozer, David J. (2024). Classical Reaction Barriers in DFT: An Adiabatic-Connection Perspective. Journal of Chemical Theory and Computation. ISSN 1549-9618. s. 1–14. doi: 10.1021/acs.jctc.4c01038. Fulltekst i vitenarkiv Vis sammendrag

  Classical reaction barriers in density-functional theory are considered from the perspective of the density-fixed adiabatic connection. A ‘reaction adiabatic-connection integrand’, ℛ𝜆, is introduced, where λ is the electron–electron interaction strength, for which ∫10ℛ𝜆d𝜆 equals the barrier, meaning the barrier can be easily visualized as the area under a plot of ℛ𝜆 vs λ. For five chemical reactions, plots of reference ℛ𝜆, calculated from Lieb maximizations at the coupled-cluster level of theory, are compared with approximate ℛ𝜆, calculated from common exchange–correlation functionals using coordinate scaling, for coupled-cluster densities. The comparison provides a simple way to visualize and understand functional-driven errors and trends in barriers from approximate functionals, while allowing a clean separation of the role of exchange and correlation contributions to the barrier. Specifically, the accuracy of ℛ0 is determined entirely by the accuracy of the exchange functional, while the shape of ℛ𝜆 is determined entirely by the correlation functional. The results clearly illustrate why the optimal amount of exact (orbital) exchange in hybrid functionals differs between reactions, including forward and reverse directions in the same reaction, and hence why simply introducing larger amounts of exact exchange may not be a reliable approach for improving barriers. Instead, the shape of ℛ𝜆 must be captured more accurately through more accurate correlation functionals, and the numerical data presented may be useful for this purpose. Density-driven errors are then considered, and possible cancellation with functional-driven errors in barriers─noted in prior studies when Hartree–Fock densities are used─is illustrated from the perspective of ℛ𝜆.

• Hou, Lin; Irons, Tom J. P.; Wang, Yanyong; Furness, James W.; Teale, Andrew Michael & Sun, Jianwei (2024). Capturing the electron-electron cusp with the coupling-constant averaged exchange-correlation hole: A case study for Hooke’s atoms. Journal of Chemical Physics. ISSN 0021-9606. 160(1). doi: 10.1063/5.0173370. Fulltekst i vitenarkiv Vis sammendrag

  In density-functional theory, the exchange–correlation (XC) energy can be defined exactly through the coupling-constant (λ) averaged XC hole nxc (r, r')⁠, representing the probability depletion of finding an electron at r′ due to an electron at r. Accurate knowledge of nxc (r, r') has been crucial for developing XC energy density-functional approximations and understanding their performance for molecules and materials. However, there are very few systems for which accurate XC holes have been calculated since this requires evaluating the one- and two-particle reduced density matrices for a reference wave function over a range of λ while the electron density remains fixed at the physical (λ = 1) density. Although the coupled-cluster singles and doubles (CCSD) method can yield exact results for a two-electron system in the complete basis set limit, it cannot capture the electron–electron cusp using finite basis sets. Focusing on Hooke’s atom as a two-electron model system for which certain analytic solutions are known, we examine the effect of this cusp error on the XC hole calculated using CCSD. The Lieb functional is calculated at a range of coupling constants to determine the λ-integrated XC hole. Our results indicate that, for Hooke’s atoms, the error introduced by the description of the electron–electron cusp using Gaussian basis sets at the CCSD level is negligible compared to the basis set incompleteness error. The system-, angle-, and coupling-constant-averaged XC holes are also calculated and provide a benchmark against which the Perdew–Burke–Ernzerhof and local density approximation XC hole models are assessed.

• Cheng, Chi Y. & Teale, Andrew Michael (2023). Semiempirical Methods for Molecular Systems in Strong Magnetic Fields. Journal of Chemical Theory and Computation. ISSN 1549-9618. 19(18), s. 6226–6241. doi: 10.1021/acs.jctc.3c00671. Fulltekst i vitenarkiv Vis sammendrag

  A general scheme is presented to extend semiempirical methods to include the effects of arbitrary strength magnetic fields, while maintaining computational efficiency. The approach utilizes three main modifications; a London atomic orbital (LAO) basis set is introduced, field-dependent kinetic energy corrections are added to the model Hamiltonian, and spin-Zeeman interaction energy terms are included. The approach is applied to the widely available density-functional tight-binding method GFN1-xTB. Considering the basis set requirements for the kinetic energy corrections in a magnetic field leads to two variants: a single-basis approach GFN1-xTB-M0 and a dual-basis approach GFN1-xTB-M1. The LAO basis in the latter includes the appropriate nodal structure for an accurate representation of the kinetic energy corrections. The variants are assessed by benchmarking magnetizabilities and nuclear magnetic resonance shielding constants calculated using weak magnetic fields. Remarkably, the GFN1-xTB-M1 approach also exhibits excellent performance for strong fields, |B| ≤ 0.2B0 (B0 = 2.3505 × 105 T), recovering exotic features such as the para- to dia-magnetic transition in the BH molecule and the preferred electronic configuration, molecular conformation, and orientation of benzene. At stronger field strengths, |B| > 0.2B0, a degradation in the quality of the results is observed. The utility of GFN1-xTB-M1 is demonstrated by performing conformer searches in a range of field strengths for the cyclooctatetraene molecule, with GFN1-xTB-M1 capturing the transition from tub to planar conformations at high field, consistent with much more computationally demanding current-density functional theory calculations. Magnetically induced currents are also shown to be well described for the benzene and infinitene molecules, the latter demonstrating the flexibility and computational efficiency of the approach. The GFN1-xTB-M1 approach is a useful tool for the study of structure, conformation, and dynamics of large systems in magnetic fields at the semiempirical level as well as for preoptimization of molecular structure in ab initio calculations, enabling more efficient exploration of complex potential energy surfaces and reactivity in the presence of external fields.

• Huynh, Bang C.; Wibowo-Teale, Meilani & Teale, Andrew Michael (2023). QSym ²: A Quantum Symbolic Symmetry Analysis Program for Electronic Structure. Journal of Chemical Theory and Computation. ISSN 1549-9618. doi: 10.1021/acs.jctc.3c01118. Fulltekst i vitenarkiv Vis sammendrag

  Symmetry provides a powerful machinery to classify, interpret, and understand quantum-mechanical theories and results. However, most contemporary quantum chemistry packages lack the ability to handle degeneracy and symmetry breaking effects, especially in non-Abelian groups, and they are not able to characterize symmetry in the presence of external magnetic or electric fields. In this article, a program written in Rust entitled QSym2 that makes use of group and representation theories to provide symmetry analysis for a wide range of quantum-chemical calculations is introduced. With its ability to generate character tables symbolically on-the-fly and by making use of a generic symmetry-orbit-based representation analysis method formulated in this work, QSym2 is able to address all of these shortcomings. To illustrate these capabilities of QSym2, four sets of case studies are examined in detail in this article: (i) high-symmetry C84H64, C60, and B9– to demonstrate the analysis of degenerate molecular orbitals (MOs); (ii) octahedral Fe(CN)63– to demonstrate the analysis of symmetry-broken determinants and MOs; (iii) linear hydrogen fluoride in a magnetic field to demonstrate the analysis of magnetic symmetry; and (iv) equilateral H3+ to demonstrate the analysis of density symmetries.

• Wibowo-Teale, Meilani; Ennifer, Benjamin J. & Teale, Andrew Michael (2023). Real-time time-dependent self-consistent field methods with dynamic magnetic fields. Journal of Chemical Physics. ISSN 0021-9606. 159(10). doi: 10.1063/5.0160317. Fulltekst i vitenarkiv Vis sammendrag

  The first finite basis set implementation of the real-time time-dependent self-consistent field method in a dynamic (time-dependent) magnetic field using London atomic orbitals (LAOs) is presented. The accuracy of the finite basis approach using LAOs is benchmarked against numerical results from the literature for the hydrogen atom and H2 in the presence of rapidly oscillating magnetic fields. This comparison is used to inform the choice of appropriate basis sets for studies under such conditions. Remarkably, relatively modest compact LAO basis sets are sufficient to obtain accurate results. Analysis of electron dynamics in the hydrogen atom shows that LAO calculations correctly capture the time evolution of orbital occupations. The Fourier transformation of the autocorrelation function yields a power spectrum exhibiting harmonics associated with coherent emission, which closely matches the literature and further confirms the accuracy of this approach. The dynamical response of the electron density in H2 for a magnetic field parallel to the internuclear axis shows similar behavior to benchmark studies. The flexibility of this implementation is then demonstrated by considering how the dynamical response changes as a function of the orientation of the molecule relative to the applied field. At non-parallel orientations, the symmetry of the system is lowered and numerical benchmark data, which exploit cylindrical symmetry, are no-longer readily available. The present study demonstrates the utility of LAO-based calculations for extreme dynamic magnetic fields, providing a stress-test on the choice of basis. Future applications of this approach for less extreme dynamic magnetic fields are briefly discussed.

• Ofstad, Benedicte; Wibowo-Teale, Meilani; Kristiansen, Håkon Emil; Aurbakken, Einar; Kitsaras, Marios-Petros & Schøyen, Øyvind Sigmundson [Vis alle 12 forfattere av denne artikkelen] (2023). Magnetic optical rotation from real-time simulations in finite magnetic fields. Journal of Chemical Physics. ISSN 0021-9606. 159(20), s. 1–14. doi: 10.1063/5.0171927. Fulltekst i vitenarkiv Vis sammendrag

  We present a numerical approach to magnetic optical rotation based on real-time time-dependent electronic-structure theory. Not relying on perturbation expansions in the magnetic-field strength, the formulation allows us to test the range of validity of the linear relation between the rotation angle per unit path length and the magnetic-field strength that was established empirically by Verdet 160 years ago. Results obtained from time-dependent coupled-cluster and time-dependent current density-functional theory are presented for the closed-shell molecules H2, HF, and CO in magnetic fields up to 55 kT at standard temperature and pressure conditions. We find that Verdet's linearity remains valid up to roughly 10-20 kT, above which significant deviations from linearity are observed. Among the three current density-functional approximations tested in this work, the current-dependent Tao-Perdew-Staroverov–Scuseria hybrid functional performs the best in comparison with time-dependent coupled-cluster singles and doubles results for the magnetic optical rotation.

• Pokharel, Kanun; Furness, James W.; Yao, Yi; Blum, Volker; Irons, Tom JP & Teale, Andrew Michael [Vis alle 7 forfattere av denne artikkelen] (2022). Exact constraints and appropriate norms in machine-learned exchange-correlation functionals. Journal of Chemical Physics. ISSN 0021-9606. 157(17). doi: 10.1063/5.0111183. Fulltekst i vitenarkiv
• Pemberton, Miles J.; Irons, Tom J. P.; Helgaker, Trygve & Teale, Andrew Michael (2022). Revealing the exotic structure of molecules in strong magnetic fields. Journal of Chemical Physics. ISSN 0021-9606. 156(20). doi: 10.1063/5.0092520. Fulltekst i vitenarkiv Vis sammendrag

  A novel implementation for the calculation of molecular gradients under strong magnetic fields is employed at the current-density functional theory level to optimize the geometries of molecular structures, which change significantly under these conditions. An analog of the ab initio random structure search is utilized to determine the ground-state equilibrium geometries for He n and CH n systems at high magnetic field strengths, revealing the most stable structures to be those in high-spin states with a planar geometry aligned perpendicular to the field. The electron and current densities for these systems have also been investigated to develop an explanation of chemical bonding in the strong field regime, providing an insight into the exotic chemistry present in these extreme environments.

• Irons, Tom JP; Huynh, Bang C.; Teale, Andrew Michael; Proft, Frank de & Geerlings, Paul (2022). Molecular charge distributions in strong magnetic fields: a conceptual and current DFT study. Molecular Physics. ISSN 0026-8976. doi: 10.1080/00268976.2022.2145245. Fulltekst i vitenarkiv Vis sammendrag

  is studied in the context of recent extensions of conceptual density functional theory to include additional variables such as external magnetic fields. From conceptual DFT studies on atoms in strong magnetic fields, changes in electronegativity and hardness suggest a reversal in polarity for all three diatomic molecules under these conditions. This is confirmed by current DFT calculations on these molecules in the presence of strong magnetic fields parallel and perpendicular to the internuclear axis; in the former case the electric dipole moment only undergoes small changes whereas in the latter case it changes significantly and also reverses in direction, doing so at lower field strength if the geometry is relaxed. The absence of a dipole moment induced perpendicular to the bond when a magnetic field is applied in this direction is understood by consideration of time reversal symmetry. Similar results are obtained for H2

• Wibowo, Meilani; Huynh, Bang C.; Cheng, Chi Y.; Irons, Tom JP & Teale, Andrew Michael (2022). Understanding ground and excited-state molecular structure in strong magnetic fields using the maximum overlap method. Molecular Physics. ISSN 0026-8976. doi: 10.1080/00268976.2022.2152748. Fulltekst i vitenarkiv Vis sammendrag

  The maximum overlap method (MOM) provides a simple but powerful approach for performing calculations on excited states by targeting solutions with non-Aufbau occupations from a reference set of molecular orbitals. In this work, the MOM is used to access excited states of H+3 and H3 in strong magnetic fields. The lowest 1A'1, 1E' and 3E' states of H+3 in the absence of a field are compared with the corresponding states in strong magnetic fields. The changes in molecular structure in the presence of the field are examined by performing excited state geometry optimisations using the MOM. The 3E' state is significantly stabilised by the field, becoming the ground state in strong fields with a preferred orientation perpendicular to the applied field. Its potential energy surface evolves from being repulsive to bound, with an equilateral equilibrium geometry. In contrast, the 1A'1 state is destabilised and its structure distorts to an isosceles form with the longest H−H bond parallel to the applied field. Comparisons are made with the 4A'2 state of H3, which also becomes bound with an equilateral geometry at high fields. The structures of the high-spin ground states are rationalised by orbital correlation diagrams constructed using constrained geometry optimisations.

• Francotte, Robin; Irons, Tom J. P.; Teale, Andrew Michael; Proft, Frank de & Geerlings, Paul (2022). Extending conceptual DFT to include external variables: the influence of magnetic fields. Chemical Science. ISSN 2041-6520. 13(18), s. 5311–5324. doi: 10.1039/d1sc07263c. Fulltekst i vitenarkiv Vis sammendrag

  An extension of conceptual DFT to include the influence of an external magnetic field is proposed in the context of a program set up to cope with the ever increasing variability of reaction conditions and concomitant reactivity. The two simplest global reactivity descriptors, the electronic chemical potential (μ) and the hardness (η), are considered for the main group atoms H–Kr using current density-functional theory. The magnetic field strength, |B|, is varied between 0.0 and 1.0 B0 = ħe−1a0−2 ≈ 2.3505 × 105 T, encompassing the Coulomb and intermediate regimes. The carbon atom is studied as an exemplar system to gain insight into the behaviour of the neutral, cationic and anionic species under these conditions. Their electronic configurations change with increasing |B|, leading to a piecewise behaviour of the ionization energy (I) and electron affinity (A) values as a function of |B|. This results in complex behaviour of properties such as the electronegativity χ = −1/2(I + A) = −μ and hardness η = 1/2(I − A). This raises an interesting question: to what extent are atomic properties periodic in the presence of a magnetic field? In the Coulomb regime, close to |B| = 0, we find the familiar periodicity of the atomic properties, and make the connections to response functions central to conceptual DFT. However, as the field increases in the intermediate regime configurational changes of the atomic species lead to discontinuous changes in their properties; fundamentally changing their behaviour, which is illustrated by constructing a periodic table of χ and η values at |B| = 0.5 B0. These values tend to increase for groups 1–2 and decrease for groups 16–18, leading to a narrower range overall and suggesting substantial changes in the chemistry of the main group elements. Changes within each group are also examined as a function of |B|. These are more complex to interpret due to the larger number of configurations accessible to heavier elements at high field. This is illustrated for group 17 where Cl and Br have qualitatively different configurations to their lighter cogener at |B| = 0.5 B0. The insight into periodic trends in strong magnetic fields may provide a crucial starting point for predicting chemical reactivity under these exotic conditions.

• Teale, Andrew Michael; Helgaker, Trygve; Savin, Andreas; Adamo, Carlo; Aradi, Balint & Arbuznikov, Alexei V. [Vis alle 70 forfattere av denne artikkelen] (2022). DFT exchange: sharing perspectives on the workhorse of quantum chemistry and materials science. Physical Chemistry, Chemical Physics - PCCP. ISSN 1463-9076. doi: 10.1039/d2cp02827a. Fulltekst i vitenarkiv Vis sammendrag

  In this paper, the history, present status, and future of density-functional theory (DFT) is informally reviewed and discussed by 70 workers in the field, including molecular scientists, materials scientists, method developers and practitioners. The format of the paper is that of a roundtable discussion, in which the participants express and exchange views on DFT in the form of 302 individual contributions, formulated as responses to a preset list of 26 questions. Supported by a bibliography of 777 entries, the paper represents a broad snapshot of DFT, anno 2022.

• Speake, Benjamin T.; Irons, Tom JP; Wibowo, Meilani; Johnson, Andrew G; David, Grégoire & Teale, Andrew Michael (2022). An Embedded Fragment Method for Molecules in Strong Magnetic Fields. Journal of Chemical Theory and Computation. ISSN 1549-9618. 18(12), s. 7412–7427. doi: 10.1021/acs.jctc.2c00865. Fulltekst i vitenarkiv Vis sammendrag

  An extension of the embedded fragment method for calculations on molecular clusters is presented, which includes strong external magnetic fields. The approach is flexible, allowing for calculations at the Hartree–Fock, current-density-functional theory, Møller–Plesset perturbation theory, and coupled-cluster levels using London atomic orbitals. For systems consisting of discrete molecular subunits, calculations using London atomic orbitals can be performed in a computationally tractable manner for systems beyond the reach of conventional calculations, even those accelerated by resolution-of-the-identity or Cholesky decomposition methods. To assess the applicability of the approach, applications to water clusters are presented, showing how strong magnetic fields enhance binding within the clusters. However, our calculations suggest that, contrary to previous suggestions in the literature, this enhanced binding may not be directly attributable to strengthening of hydrogen bonding. Instead, these results suggest that this arises for larger field strengths as a response of the system to the presence of the external field, which induces a charge density build up between the monomer units. The approach is embarrassingly parallel and its computational tractability is demonstrated for clusters of up to 103 water molecules in triple-ζ basis sets, which would correspond to conventional calculations with more than 12 000 basis functions.

• Ryley, Matthew S.; Withnall, Michael; Irons, Tom J. P.; Helgaker, Trygve & Teale, Andrew Michael (2021). Robust All-Electron Optimization in Orbital-Free Density-Functional Theory Using the Trust-Region Image Method. Journal of Physical Chemistry A. ISSN 1089-5639. 125(1), s. 459–475. doi: 10.1021/acs.jpca.0c09502. Fulltekst i vitenarkiv
• David, Grégoire; Irons, Tom J. P.; Fouda, Adam E. A.; Furness, James W. & Teale, Andrew Michael (2021). Self-Consistent Field Methods for Excited States in Strong Magnetic Fields: A Comparison between Energy-and Variance-Based Approaches. Journal of Chemical Theory and Computation. ISSN 1549-9618. doi: 10.1021/acs.jctc.1c00236. Fulltekst i vitenarkiv Vis sammendrag

  Self-consistent field methods for excited states offer an attractive low-cost route to study not only excitation energies but also properties of excited states. Here, we present the generalization of two self-consistent field methods, the maximum overlap method (MOM) and the σ-SCF method, to calculate excited states in strong magnetic fields and investigate their stability and accuracy in this context. These methods use different strategies to overcome the well-known variational collapse of energy-based optimizations to the lowest solution of a given symmetry. The MOM tackles this problem in the definition of the orbital occupations to constrain the self-consistent field procedure to converge on excited states, while the σ-SCF method is based on the minimization of the variance instead of the energy. To overcome the high computational cost of the variance minimization, we present a new implementation of the σ-SCF method with the resolution of identity approximation, allowing the use of large basis sets, which is an important requirement for calculations in strong magnetic fields. The accuracy of these methods is assessed by comparison with the benchmark literature data for He, H2, and CH+. The results reveal severe limitations of the variance-based scheme, which become more acute in large basis sets. In particular, many states are not accessible using variance optimization. Detailed analysis shows that this is a general feature of variance optimization approaches due to the masking of local minima in the optimization. In contrast, the MOM shows promising performance for computing excited states under these conditions, yielding results consistent with available benchmark data for a diverse range of electronic states.

• Irons, Tom J. P.; Garner, Adam & Teale, Andrew Michael (2021). Topological Analysis of Magnetically Induced Current Densities in Strong Magnetic Fields Using Stagnation Graphs. Chemistry. 3(3), s. 916–934. doi: 10.3390/chemistry3030067. Fulltekst i vitenarkiv Vis sammendrag

  Stagnation graphs provide a useful tool to analyze the main topological features of the often complicated vector field associated with magnetically induced currents. Previously, these graphs have been constructed using response quantities appropriate for modest applied magnetic fields. We present an implementation capable of producing these graphs in arbitrarily strong magnetic fields, using current-density-functional theory. This enables us to study how the topology of the current vector field changes with the strength and orientation of the applied magnetic field. Applications to CH4, C2H2 and C2H4 are presented. In each case, we consider molecular geometries optimized in the presence of the magnetic field. The stagnation graphs reveal subtle changes to this vector field where the symmetry of the molecule remains constant. However, when the electronic state and symmetry of the corresponding equilibrium geometry changes with increasing field strength, the changes to the stagnation graph are extensive. We expect that the approach presented here will be helpful in interpreting changes in molecular structure and bonding in the strong-field regime.

• Irons, Tom J. P.; David, Grégoire & Teale, Andrew Michael (2021). Optimizing Molecular Geometries in Strong Magnetic Fields. Journal of Chemical Theory and Computation. ISSN 1549-9618. 17(4), s. 2166–2185. doi: 10.1021/acs.jctc.0c01297. Fulltekst i vitenarkiv Vis sammendrag

  An efficient implementation of geometrical derivatives at the Hartree–Fock (HF) and current-density functional theory (CDFT) levels is presented for the study of molecular structure in strong magnetic fields. The required integral derivatives are constructed using a hybrid McMurchie–Davidson and Rys quadrature approach, which combines the amenability of the former to the evaluation of derivative integrals with the efficiency of the latter for basis sets with high angular momentum. In addition to its application to evaluating derivatives of four-center integrals, this approach is also applied to gradients using the resolution-of-the-identity approximation, enabling efficient optimization of molecular structure for many-electron systems under a strong magnetic field. The CDFT contributions have been implemented for a wide range of density functionals up to and including the meta-GGA level with current-density dependent contributions and (range-separated) hybrids for the first time. Illustrative applications are presented to the OH and benzene molecules, revealing the rich and complex chemistry induced by the presence of an external magnetic field. Challenges for geometry optimization in strong fields are highlighted, along with the requirement for careful analysis of the resulting electronic structure at each stationary point. The importance of correlation effects is examined by comparison of results at the HF and CDFT levels. The present implementation of molecular gradients at the CDFT level provides a cost-effective approach to the study of molecular structure under strong magnetic fields, opening up many new possibilities for the study of chemistry in this regime.

• Wibowo, Meilani; Irons, Tom J. P. & Teale, Andrew Michael (2021). Modeling Ultrafast Electron Dynamics in Strong Magnetic Fields Using Real-Time Time-Dependent Electronic Structure Methods. Journal of Chemical Theory and Computation. ISSN 1549-9618. 17(4), s. 2137–2165. doi: 10.1021/acs.jctc.0c01269. Fulltekst i vitenarkiv Vis sammendrag

  An implementation of real-time time-dependent Hartree–Fock (RT-TDHF) and current density functional theory (RT-TDCDFT) for molecules in strong uniform magnetic fields is presented. In contrast to earlier implementations, the present work enables the use of the RT-TDCDFT formalism, which explicitly includes field-dependent terms in the exchange–correlation functional. A range of current-dependent exchange–correlation functionals based on the TPSS functional are considered, including a range-separated variant, which is particularly suitable for application to excited state calculations. The performance of a wide range of propagator algorithms for real-time methods is investigated in this context. A recently proposed molecular orbital pair decomposition analysis allows for assignment of electronic transitions, providing detailed information about which molecular orbitals are involved in each excitation. The application of these methods is demonstrated for the electronic absorption spectra of N2 and H2O both in the absence and in the presence of a magnetic field. The dependence of electronic spectra on the magnetic field strength and its orientation relative to the molecule is studied. The complex evolution of the absorption spectra with magnetic field is rationalized using the molecular orbital pair decomposition analysis, which provides crucial insight in strong fields where the spectra are radically different from their zero-field counterparts.

• Irons, Tom J P; Spence, Lucy; Speake, Gregoire David; Speake, Benjamin T.; Helgaker, Trygve & Teale, Andrew Michael (2020). Analyzing Magnetically Induced Currents in Molecular Systems Using Current-Density-Functional Theory. Journal of Physical Chemistry A. ISSN 1089-5639. 124, s. 1321–1333. doi: 10.1021/acs.jpca.9b10833. Fulltekst i vitenarkiv
• Brandenburg, Jan Gerit; Burke, Kieron; Fromager, Emmanuel; Gatti, Matteo; Giarrusso, Sara & Gidopoulos, Nikitas I. [Vis alle 29 forfattere av denne artikkelen] (2020). New approaches to study excited states in density functional theory: general discussion. Faraday discussions. ISSN 1359-6640. 224, s. 483–508. doi: 10.1039/D0FD90026E. Fulltekst i vitenarkiv
• Brandenburg, Jan Gerit; Burke, Kieron; Cancio, Antonio; Erhard, Jannis; Fromager, Emmanuel & Ghosal, Abhisek [Vis alle 25 forfattere av denne artikkelen] (2020). New density-functional approximations and beyond: general discussion. Faraday discussions. ISSN 1359-6640. 224, s. 166–200. doi: 10.1039/D0FD90023K. Fulltekst i vitenarkiv
• Holzer, Christof; Teale, Andrew Michael; Hampe, Florian; Stopkowicz, Stella; Helgaker, Trygve & Klopper, Wim (2019). GW quasiparticle energies of atoms in strong magnetic fields. Journal of Chemical Physics. ISSN 0021-9606. 150(21), s. 214112-1–214112-9. doi: 10.1063/1.5093396. Fulltekst i vitenarkiv
• Reimann, Sarah; Borgoo, Alex; Austad, Jon; Tellgren, Erik; Teale, Andrew Michael & Helgaker, Trygve [Vis alle 7 forfattere av denne artikkelen] (2019). Kohn–Sham energy decomposition for molecules in a magnetic field. Molecular Physics. ISSN 0026-8976. 117(1), s. 97–109. doi: 10.1080/00268976.2018.1495849. Fulltekst i vitenarkiv
• Tellgren, Erik; Laestadius, Andre; Helgaker, Trygve; Kvaal, Simen & Teale, Andrew Michael (2018). Uniform magnetic fields in density-functional theory. Journal of Chemical Physics. ISSN 0021-9606. 148(2), s. 1–19. doi: 10.1063/1.5007300. Fulltekst i vitenarkiv
• Rebolini, Elisa; Teale, Andrew Michael; Helgaker, Trygve; Savin, Andreas & Toulouse, Julien (2018). Excitation energies from Gorling?Levy perturbation theory along the range-separated adiabatic connection. Molecular Physics. ISSN 0026-8976. 116(11), s. 1443–1451. doi: 10.1080/00268976.2017.1422811. Fulltekst i vitenarkiv
• Kumar, Chandan; Fliegl, Heike; Jensen, Frank; Teale, Andrew Michael; Reine, Simen Sommerfelt & Kjærgaard, Thomas (2018). Accelerating Kohn‐Sham response theory using density fitting and the auxiliary‐density‐matrix method. International Journal of Quantum Chemistry. ISSN 0020-7608. 118(16), s. 1–21. doi: 10.1002/qua.25639. Fulltekst i vitenarkiv Vis sammendrag

  An extension of the formulation of the atomic‐orbital‐based response theory of Larsen et al., JCP 113, 8909 (2000) is presented. This new framework has been implemented in LSDalton and allows for the use of Kohn‐Sham density‐functional theory with approximate treatment of the Coulomb and Exchange contributions to the response equations via the popular resolution‐of‐the‐identity approximation as well as the auxiliary‐density matrix method (ADMM). We present benchmark calculations of ground‐state energies as well as the linear and quadratic response properties: vertical excitation energies, polarizabilities, and hyperpolarizabilities. The quality of these approximations in a range of basis sets is assessed against reference calculations in a large aug‐pcseg‐4 basis. Our results confirm that density fitting of the Coulomb contribution can be used without hesitation for all the studied properties. The ADMM treatment of exchange is shown to yield high accuracy for ground‐state and excitation energies, whereas for polarizabilities and hyperpolarizabilities the performance gain comes at a cost of accuracy. Excitation energies of a tetrameric model consisting of units of the P700 special pigment of photosystem I have been studied to demonstrate the applicability of the code for a large system.

• Reimann, Sarah; Borgoo, Alex; Tellgren, Erik; Teale, Andrew Michael & Helgaker, Trygve (2017). Magnetic-Field Density-Functional Theory (BDFT): Lessons from the Adiabatic Connection. Journal of Chemical Theory and Computation. ISSN 1549-9618. 13(9), s. 4089–4100. doi: 10.1021/acs.jctc.7b00295. Fulltekst i vitenarkiv Vis sammendrag

  We study the effects of magnetic fields in the context of magnetic field density-functional theory (BDFT), where the energy is a functional of the electron density ρ and the magnetic field B. We show that this approach is a worthwhile alternative to current-density functional theory (CDFT) and may provide a viable route to the study of many magnetic phenomena using density-functional theory (DFT). The relationship between BDFT and CDFT is developed and clarified within the framework of the four-way correspondence of saddle functions and their convex and concave parents in convex analysis. By decomposing the energy into its Kohn–Sham components, we demonstrate that the magnetizability is mainly determined by those energy components that are related to the density. For existing density functional approximations, this implies that, for the magnetizability, improvements of the density will be more beneficial than introducing a magnetic-field dependence in the correlation functional. However, once a good charge density is achieved, we show that high accuracy is likely only obtainable by including magnetic-field dependence. We demonstrate that adiabatic-connection (AC) curves at different field strengths resemble one another closely provided each curve is calculated at the equilibrium geometry of that field strength. In contrast, if all AC curves are calculated at the equilibrium geometry of the field-free system, then the curves change strongly with increasing field strength due to the increasing importance of static correlation. This holds also for density functional approximations, for which we demonstrate that the main error encountered in the presence of a field is already present at zero field strength, indicating that density-functional approximations may be applied to systems in strong fields, without the need to treat additional static correlation. The final version of this research has been published in Journal of Chemical Theory and Computation. © 2017 American Chemical Society

• Irons, Tom J P; Furness, James W.; Ryley, Matthew S.; Zemen, Jan; Helgaker, Trygve & Teale, Andrew Michael (2017). Connections between variation principles at the interface of wave-function and density-functional theories. Journal of Chemical Physics. ISSN 0021-9606. 147(13). doi: 10.1063/1.4985883. Fulltekst i vitenarkiv Vis sammendrag

  A recently proposed variation principle [N. I. Gidopoulos, Phys. Rev. A 83, 040502(R) (2011)] for the determination of Kohn–Sham effective potentials is examined and extended to arbitrary electron-interaction strengths and to mixed states. Comparisons are drawn with Lieb’s convex-conjugate functional, which allows for the determination of a potential associated with a given electron density by maximization, yielding the Kohn–Sham potential for a non-interacting system. The mathematical structure of the two functionals is shown to be intrinsically related; the variation principle put forward by Gidopoulos may be expressed in terms of the Lieb functional. The equivalence between the information obtained from the two approaches is illustrated numerically by their implementation in a common framework. This article was originally published in the Journal of Chemical Physics. © 2017 AIP Publishing

• Teale, Andrew Michael; Helgaker, Trygve & Savin, Andreas (2016). Alternative Representations of the Correlation Energy in Density-Functional Theory: A Kinetic-Energy Based Adiabatic Connection. Journal of the Chinese Chemical Society (Taipei). ISSN 0009-4536. 63(1), s. 121–128. doi: 10.1002/jccs.201500132. Fulltekst i vitenarkiv
• Furness, James W.; Ekström, Ulf Egil; Helgaker, Trygve & Teale, Andrew Michael (2016). Electron localisation function in current-density-functional theory. Molecular Physics. ISSN 0026-8976. 114(7-8), s. 1415–1422. doi: 10.1080/00268976.2015.1133859. Fulltekst i vitenarkiv
• Reimann, Sarah; Ekström, Ulf Egil; Stopkowicz, Stella; Teale, Andrew Michael; Borgoo, Alex & Helgaker, Trygve (2015). The importance of current contributions to shielding constants in density-functional theory. Physical Chemistry, Chemical Physics - PCCP. ISSN 1463-9076. 17(28), s. 18834–18842. doi: 10.1039/c5cp02682b. Fulltekst i vitenarkiv
• Rebolini, Elisa; Toulouse, Julien; Teale, Andrew Michael; Helgaker, Trygve & Savin, Andreas (2015). Excited states from a range-separated density-functional perturbation theory. Molecular Physics. ISSN 0026-8976. 113(13-14), s. 1740–1749. doi: 10.1080/00268976.2015.1011248. Fulltekst i vitenarkiv
• Borgoo, Alex; Teale, Andrew Michael & Helgaker, Trygve (2015). Excitation energies from ensemble DFT. AIP Conference Proceedings. ISSN 0094-243X. 1702:090049. doi: 10.1063/1.4938857. Fulltekst i vitenarkiv
• Cheng, Chi Y.; Ryley, Matthew S.; Peach, Michael J.G.; Tozer, David J.; Helgaker, Trygve & Teale, Andrew Michael (2015). Molecular properties in the Tamm–Dancoff approximation: indirect nuclear spin–spin coupling constants. Molecular Physics. ISSN 0026-8976. 113(13-14), s. 1937–1951. doi: 10.1080/00268976.2015.1024182. Fulltekst i vitenarkiv
• Peach, Michael J. G.; Teale, Andrew Michael; Helgaker, Trygve & Tozer, David J. (2015). Fractional electron loss in approximate DFT and Hartree-Fock theory. Journal of Chemical Theory and Computation. ISSN 1549-9618. 11(11), s. 5262–5268. doi: 10.1021/acs.jctc.5b00804. Fulltekst i vitenarkiv
• Rebolini, Elisa; Toulouse, Julien; Teale, Andrew Michael; Helgaker, Trygve & Savin, A (2015). Calculating excitation energies by extrapolation along adiabatic connections. Physical Review A. Atomic, Molecular, and Optical Physics (PRA). ISSN 1050-2947. 91. doi: 10.1103/PhysRevA.91.032519. Fulltekst i vitenarkiv Vis sammendrag

  In this paper, an alternative method to range-separated linear-response time-dependent density-functional theory and perturbation theory is proposed to improve the estimation of the energies of a physical system from the energies of a partially interacting system. Starting from the analysis of the Taylor expansion of the energies of the partially interacting system around the physical system, we use an extrapolation scheme to improve the estimation of the energies of the physical system at an intermediate point of the range-separated or linear adiabatic connection where either the electron–electron interaction is scaled or only the long-range part of the Coulomb interaction is included. The extrapolation scheme is first applied to the range-separated energies of the helium and beryllium atoms and of the hydrogen molecule at its equilibrium and stretched geometries. It improves significantly the convergence rate of the energies toward their exact limit with respect to the range-separation parameter. The range-separated extrapolation scheme is compared with a similar approach for the linear adiabatic connection, highlighting the relative strengths and weaknesses of each approach. © 2015 American Physical Society

• Furness, James W.; Verbeke, Joachim; Tellgren, Erik; Stopkowicz, Stella; Ekström, Ulf Egil & Helgaker, Trygve [Vis alle 7 forfattere av denne artikkelen] (2015). Current density functional theory using meta-generalized gradient exchange-correlation functionals. Journal of Chemical Theory and Computation. ISSN 1549-9618. 11(9), s. 4169–4181. doi: 10.1021/acs.jctc.5b00535. Fulltekst i vitenarkiv
• Kvaal, Simen; Ekström, Ulf Egil; Teale, Andrew Michael & Helgaker, Trygve (2014). Differentiable but exact formulation of density-functional theory. Journal of Chemical Physics. ISSN 0021-9606. 140(18). doi: 10.1063/1.4867005. Fulltekst i vitenarkiv
• Tellgren, Erik; Teale, Andrew Michael; Furness, J.W.; Lange, Kai Kaarvann; Ekström, Ulf Egil & Helgaker, Trygve (2014). Non-perturbative calculation of molecular magnetic properties within current-density functional theory. Journal of Chemical Physics. ISSN 0021-9606. 140(3). doi: 10.1063/1.4861427. Fulltekst i vitenarkiv
• Grabowski, Ireneusz; Teale, Andrew Michael; Fabiano, Eduardo; Smiga, Szymon; Buksztel, Adam & Sala, Fabio Della (2014). A density difference based analysis of orbital-dependent exchange-correlation functionals. Molecular Physics. ISSN 0026-8976. 112(5-6), s. 700–710. doi: 10.1080/00268976.2013.854424. Fulltekst i vitenarkiv
• Turpin, Eleanor; Mulholland, Sam; Teale, Andrew Michael; Bonev, Boyan & Hirst, Jonathan (2014). New CHARMM force field parameters for dehydrated amino acid residues, the key to lantibiotic molecular dynamics simulations. RSC Advances. 4, s. 48621–48631. doi: 10.1039/c4ra09897h. Fulltekst i vitenarkiv
• Teale, Andrew Michael; DeProft, Frank; Geerlings, Paul & Tozer, David J. (2014). Atomic electron affinities and the role of symmetry between electron addition and subtraction in a corrected Koopmans approach. Physical Chemistry, Chemical Physics - PCCP. ISSN 1463-9076. 16(28), s. 14420–14434. doi: 10.1039/c3cp54528h. Fulltekst i vitenarkiv
• Grabowski, Ireneusz; Fabiano, Eduardo; Teale, Andrew Michael; Śmiga, Szymon; Buksztel, Adam & Sala, Fabio Della (2014). Orbital-dependent second-order scaled-opposite-spin correlation functionals in the optimized effective potential method. Journal of Chemical Physics. ISSN 0021-9606. 141(2). doi: 10.1063/1.4887097. Fulltekst i vitenarkiv
• Borgoo, Alex; Teale, Andrew Michael & Tozer, David J. (2014). Revisiting the density scaling of the non-interacting kinetic energy. Physical Chemistry, Chemical Physics - PCCP. ISSN 1463-9076. 16, s. 14578–14583. doi: 10.1039/C4CP00170B. Fulltekst i vitenarkiv
• Rebolini, Elisa; Toulouse, Julien; Teale, Andrew Michael; Helgaker, Trygve & Savin, Andreas (2014). Excitation energies along a range-separated adiabatic connection. Journal of Chemical Physics. ISSN 0021-9606. 141(4). doi: 10.1063/1.4890652. Fulltekst i vitenarkiv
• Komasa, Jacek; Slupski, R; Jankowski, K; Wasilewski, J & Teale, Andrew Michael (2013). High accuracy ab initio studies of electron-densities for the ground state of Be-like atomic systems. Journal of Chemical Physics. ISSN 0021-9606. 138(16). doi: 10.1063/1.4800766. Fulltekst i vitenarkiv
• Rekkedal, Johannes Andreas; Coriani, Sonia; Iozzi, Maria Francesca; Teale, Andrew Michael; Helgaker, Trygve & Pedersen, Thomas Bondo (2013). Communication: Analytic gradients in the random-phase approximation. Journal of Chemical Physics. ISSN 0021-9606. 139(8). doi: 10.1063/1.4819399. Fulltekst i vitenarkiv
• Stoyanova, Alexandrina; Teale, Andrew Michael; Toulouse, Julien; Helgaker, Trygve & Fromager, Emmanuel (2013). Alternative separation of exchange and correlation energies in multi-configuration range-separated density-functional theory. Journal of Chemical Physics. ISSN 0021-9606. 139(13). doi: 10.1063/1.4822135. Fulltekst i vitenarkiv
• Cornaton, Yann; Franck, Odile; Teale, Andrew Michael & Fromager, Emmanuel (2013). Analysis of double-hybrid density functionals along the adiabatic connection. Molecular Physics. ISSN 0026-8976. 111(9-11), s. 1275–1294. doi: 10.1080/00268976.2013.783640. Fulltekst i vitenarkiv
• Teale, Andrew Michael; Lutnæs, Ola Berg; Helgaker, Trygve; Tozer, David J. & Gauss, Jürgen (2013). Benchmarking density-functional theory calculations of NMR shielding constants and spin-rotation constants using accurate coupled-cluster calculations. Journal of Chemical Physics. ISSN 0021-9606. 138(2). doi: 10.1063/1.4773016. Fulltekst i vitenarkiv
• Borgoo, Alex; Teale, Andrew Michael & Tozer, David J. (2012). Effective homogeneity of the exchange-correlation and non-interacting kinetic energy functionals under density scaling. Journal of Chemical Physics. ISSN 0021-9606. 136(3). doi: 10.1063/1.3676722. Fulltekst i vitenarkiv
• Teale, Andrew Michael; Coriani, Sonia & Helgaker, Trygve (2012). Range-dependent adiabatic connections. AIP Conference Proceedings. ISSN 0094-243X. 1504, s. 92–99. doi: 10.1063/1.4771706. Fulltekst i vitenarkiv Vis sammendrag

  Recently, we have implemented a scheme for the calculation of the adiabatic connection linking the Kohn-Sham system to the physical, interacting system. This scheme uses a generalized Lieb functional, in which the electronic-interaction strength is varied in a simple linear fashion, keeping the potential or the density fixed in the process. In the present work, we generalize this scheme further to accommodate arbitrary two-electron operators, allowing the calculation of adiabatic connections following alternative paths as outlined by Yang [J. Chem. Phys. 109, 10107 (1998)]. Specifically, we examine the error-function and Gaussian-attenuated error-function adiabatic connections. We explore the high-density and strong static-correlation regimes for two-electron systems. The resulting adiabatic connections give an alternative view of the exchange- correlation problem and their utility for the development of new exchange-correlation functionals in Kohn-Sham and rangeseparated hybrid schemes is discussed. This research was originally published in AIP Conference Proceedings. © AIP Publishing

• Tellgren, Erik; Kvaal, Simen; Sagvolden, Espen; Ekström, Ulf Egil; Teale, Andrew Michael & Helgaker, Trygve (2012). Choice of basic variables in current-density-functional theory. Physical Review A. Atomic, Molecular, and Optical Physics (PRA). ISSN 1050-2947. 86(6). doi: 10.1103/PhysRevA.86.062506. Fulltekst i vitenarkiv Vis sammendrag

  The selection of basic variables in current-density-functional theory and formal properties of the resulting formulations are critically examined. Focus is placed on the extent to which the Hohenberg-Kohn theorem, constrained-search approach, and Lieb's formulation (in terms of convex and concave conjugation) of standard density-functional theory can be generalized to provide foundations for current-density-functional theory. For the well-known case with the gauge-dependent paramagnetic current density as a basic variable, we find that the resulting total energy functional is not concave. It is shown that a simple redefinition of the scalar potential restores concavity and enables the application of convex analysis and convex (or concave) conjugation. As a result, the solution sets arising in potential-optimization problems can be given a simple characterization. We also review attempts to establish theories with the physical current density as a basic variable. Despite the appealing physical motivation behind this choice of basic variables, we find that the mathematical foundations of the theories proposed to date are unsatisfactory. Moreover, the analogy to standard density-functional theory is substantially weaker as neither the constrained-search approach nor the convex analysis framework carry over to a theory making use of the physical current density. © 2012 American Physical Society

• Grabowski, Ireneusz; Teale, Andrew Michael; Smiga, Szymon & Bartlett, Rodney J. (2011). Comparing ab initio density-functional and wave function theories: The impact of correlation on the electronic density and the role of the correlation potential. Journal of Chemical Physics. ISSN 0021-9606. 135(11). doi: 10.1063/1.3636114. Fulltekst i vitenarkiv
• Klopper, Wim; Teale, Andrew Michael; Coriani, Sonia; Pedersen, Thomas Bondo & Helgaker, Trygve (2011). Spin flipping in ring-coupled-cluster-doubles theory. Chemical Physics Letters. ISSN 0009-2614. 510(1-3), s. 147–153. doi: 10.1016/j.cplett.2011.04.101. Fulltekst i vitenarkiv
• Strømsheim, Marie Døvre; Kumar, Neena Theresa; Coriani, Sonia; Sagvolden, Espen; Teale, Andrew Michael & Helgaker, Trygve (2011). Dispersion interactions in density-functional theory: An adiabatic-connection analysis. Journal of Chemical Physics. ISSN 0021-9606. 135(19). doi: 10.1063/1.3660357. Fulltekst i vitenarkiv
• Teale, Andrew Michael; Coriani, Sonia & Helgaker, Trygve (2010). Range-dependent adiabatic connections. Journal of Chemical Physics. ISSN 0021-9606. 133(16). doi: 10.1063/1.3488100. Fulltekst i vitenarkiv
• Teale, Andrew Michael; Coriani, Sonia & Helgaker, Trygve (2010). Accurate calculation and modeling of the adiabatic connection in density functional theory. Journal of Chemical Physics. ISSN 0021-9606. 132(16). doi: 10.1063/1.3380834. Fulltekst i vitenarkiv
• Peach, Michael J. G.; Kattirtzi, JA; Teale, Andrew Michael & Tozer, David J. (2010). Shielding Constants and Chemical Shifts in DFT: Influence of Optimized Effective Potential and Coulomb-Attenuation. Journal of Physical Chemistry A. ISSN 1089-5639. 114(26), s. 7179–7186. doi: 10.1021/jp102465x. Fulltekst i vitenarkiv
• Teale, Andrew Michael; Coriani, Sonia & Helgaker, Trygve (2009). The calculation of adiabatic-connection curves from full configuration-interaction densities: Two-electron systems. Journal of Chemical Physics. ISSN 0021-9606. 130(10). doi: 10.1063/1.3082285. Fulltekst i vitenarkiv
• Lutnæs, Ola B.; Teale, AM; Helgaker, Trygve; Tozer, DJ; Ruud, Kenneth & Gauss, J (2009). Benchmarking density-functional-theory calculations of rotational g tensors and magnetizabilities using accurate coupled-cluster calculations. Journal of Chemical Physics. ISSN 0021-9606. 131(14). doi: 10.1063/1.3242081. Fulltekst i vitenarkiv
• Teale, Andrew Michael; Proft, F De & Tozer, DJ (2008). Orbital energies and negative electron affinities from density functional theory: Insight from the integer discontinuity. Journal of Chemical Physics. ISSN 0021-9606. 129. doi: 10.1063/1.2961035. Fulltekst i vitenarkiv
• Soncini, Alessandro; Teale, Andrew Michael; Helgaker, Trygve; Proft, F De & Tozer, DJ (2008). Maps of current density using density-functional methods. Journal of Chemical Physics. ISSN 0021-9606. 129. doi: 10.1063/1.2969104. Fulltekst i vitenarkiv
• Peach, MJG; Miller, AM; Teale, Andrew Michael & Tozer, DJ (2008). Adiabatic connection forms in density functional theory: H-2 and the He isoelectronic series. Journal of Chemical Physics. ISSN 0021-9606. 129. doi: 10.1063/1.2965531. Fulltekst i vitenarkiv
• Peach, Michael J. G.; Teale, Andrew Michael & Tozer, DJ (2007). Modeling the adiabatic connection in H_2. Journal of Chemical Physics. ISSN 0021-9606. 126. doi: 10.1063/1.2747248. Fulltekst i vitenarkiv

Se alle arbeider i NVA

• Teale, Andrew Michael (2022). Robust All-Electron Optimization in Orbital-Free Density-Functional Theory using the 
Trust-Region Image Method. Fulltekst i vitenarkiv
• Teale, Andrew Michael (2022). Current Density-Functional Theory for Atoms and Molecules in Strong Magnetic Fields. Fulltekst i vitenarkiv
• Teale, Andrew Michael (2022). Analyzing Magnetically Induced Currents in Molecular Systems Using Current-Density-Functional Theory. Fulltekst i vitenarkiv
• Holzer, Christof; Teale, Andrew Michael; Hampe, Florian; Stopkowicz, Stella; Helgaker, Trygve & Klopper, Wim (2019). Erratum: GW quasiparticle energies of atoms in strong magnetic fields (Journal of Chemical Physics (2019) 150 (214112) DOI: 10.1063/1.5093396). Journal of Chemical Physics. ISSN 0021-9606. 151(6). doi: 10.1063/1.5120100. Fulltekst i vitenarkiv
• Helgaker, Trygve; Borgoo, Alex; Dimitrova, Maria; Gauss, Jurgen; Hampe, Florian & Holzer, Christof [Vis alle 13 forfattere av denne artikkelen] (2018). Diamagnetism and Paramagnetism in Atoms and Molecules. Fulltekst i vitenarkiv
• Helgaker, Trygve; Borgoo, Alex; Gauss, Jurgen; Hampe, Florian; Klopper, Wim & Reimann, Sarah [Vis alle 9 forfattere av denne artikkelen] (2018). Closed-Shell Molecular Paramagnetism. Fulltekst i vitenarkiv
• Borgoo, Alex; Tozer, David J.; Teale, Andrew Michael & Helgaker, Trygve (2016). Approximate orbital-free non-interacting kinetic energy density functionals from density scaling. Fulltekst i vitenarkiv
• Tellgren, Erik; Teale, Andrew Michael; Ekström, Ulf Egil; Kvaal, Simen; Sagvolden, Espen & Helgaker, Trygve (2015). Current density functional theory for molecular systems in strong magnetic fields. Fulltekst i vitenarkiv
• Borgoo, Alex; Teale, Andrew Michael & Helgaker, Trygve (2015). Excitation energies from ensemble DFT. Fulltekst i vitenarkiv
• Borgoo, Alex; Teale, Andrew Michael & Helgaker, Trygve (2015). Excitation energies from ensemble DFT. Fulltekst i vitenarkiv
• Borgoo, Alex; Teale, Andrew Michael & Helgaker, Trygve (2014). Ensemble energies: An alternative route to excitation energies. Fulltekst i vitenarkiv
• Teale, Andrew Michael; Furness, James; Tellgren, Erik; Ekström, Ulf Egil & Helgaker, Trygve (2014). Density Functional Theory for Molecules in Magnetic Fields. Fulltekst i vitenarkiv
• Pedersen, Thomas Bondo; Rekkedal, Johannes Andreas; Leikanger, Karl R.; Iozzi, Maria Francesca; Coriani, Sonia & Teale, Andrew Michael [Vis alle 7 forfattere av denne artikkelen] (2014). Molecular Properties in the Random Phase Approximation. Fulltekst i vitenarkiv
• Helgaker, Trygve; Kvaal, Simen; Teale, Andrew Michael & Ekström, Ulf Egil (2014). Differentiable but Exact Formulation of Density-Functional Theory. Fulltekst i vitenarkiv
• Helgaker, Trygve; Kvaal, Simen; Ekström, Ulf Egil & Teale, Andrew Michael (2014). Differentiable but Exact Formulation of Density-Functional Theory. Fulltekst i vitenarkiv
• Helgaker, Trygve; Kvaal, Simen; Teale, Andrew Michael; Ekström, Ulf Egil; Jørgensen, Poul & Olsen, Jeppe (2014). Differentiable but Exact Formulation of Density-Functional Theory. Fulltekst i vitenarkiv
• Helgaker, Trygve; Borgoo, Alex; Ekström, Ulf Egil; Furness, James; Hoffmann, Mark & Kvaal, Simen [Vis alle 12 forfattere av denne artikkelen] (2014). Density-Functional Theory in Magnetic Fields. Fulltekst i vitenarkiv
• Borgoo, Alex; Savin, A; Knecht, Stefan; Teale, Andrew Michael; Helgaker, Trygve & Sagvolden, Espen (2013). Adiabatic connection for ensemble energies: \\An alternative route to excitation energies. Fulltekst i vitenarkiv
• Borgoo, Alex; Sagvolden, Espen; Teale, Andrew Michael; Knecht, Stefan; Savin, A & Helgaker, Trygve (2013). Adiabatic connection for ensemble energies: \\An alternative route to excitation energies. Fulltekst i vitenarkiv
• Borgoo, Alex; Teale, Andrew Michael & Tozer, David J. (2013). Homogeneity under density scaling and kinetic energy of the non-interacting system. Fulltekst i vitenarkiv
• Pedersen, Thomas Bondo; Rekkedal, Johannes Andreas; Iozzi, Maria Francesca; Coriani, Sonia; Teale, Andrew Michael & Helgaker, Trygve (2013). Molecular Properties in the Random Phase Approximation. Fulltekst i vitenarkiv
• Sagvolden, Espen; Tellgren, Erik; Kvaal, Simen; Ekström, Ulf Egil; Teale, Andrew Michael & Helgaker, Trygve (2013). Building blocks of Current Density Functional Theory. Fulltekst i vitenarkiv
• Sagvolden, Espen; Tellgren, Erik; Kvaal, Simen; Ekström, Ulf Egil; Teale, Andrew Michael & Helgaker, Trygve (2013). Building blocks of Current Density Functional Theory. Fulltekst i vitenarkiv
• Teale, Andrew Michael (2008). Calculating accurate adiabatic connection curves from ab initio electronic densities. Fulltekst i vitenarkiv
• Teale, Andrew Michael (2007). Optimized Effective Potentials for Orbital Dependent Functionals in DFT. Fulltekst i vitenarkiv
• Teale, Andrew Michael (2007). Poster Presentation : CDFT2007. Fulltekst i vitenarkiv
• Teale, Andrew Michael (2007). Transition Metal NMR Chemical Shifts From Optimized Effective Potentials. Fulltekst i vitenarkiv
• Teale, Andrew Michael (2007). Poster Presentation : ESQC 07. Fulltekst i vitenarkiv

Se alle arbeider i NVA