Dario Alejandro Leon Valido

• Kristian, Berland,; Claudia, Cardoso, & Valido, Dario Alejandro Leon (2026). [2606.12274] Plasmonic properties and correlation energies from a compact multipole representation of the dielectric response in 2D metals. http://arxiv.org/abs/cond-mat. Fulltekst i vitenarkiv Vis sammendrag

  Abstract page for arXiv paper 2606.12274: Plasmonic properties and correlation energies from a compact multipole representation of the dielectric response in 2D metals

• Bonacci, M.; Leon, D. A.; Spallanzani, N.; Molinari, E.; Varsano, D. & Ferretti, A. [Vis alle 7 forfattere av denne artikkelen] (2026). Benchmarking the Plasmon-Pole and Multipole Approximations in the Yambo Code Using the GW100 Data Set. Journal of Chemical Theory and Computation. ISSN 1549-9618. 22(13), s. 6718–6730. doi: 10.1021/acs.jctc.6c00239. Fulltekst i vitenarkiv Vis sammendrag

  Verification and validation of electronic structure codes are essential to ensure reliable and reproducible results in computational materials science. Besides the extensive work on density functional theory, in the field of many-body perturbation theory, the GW100 data set represents a key effort to benchmark and validate methods such as the GW approximation. In this work, we assess the numerical accuracy and convergence behavior of the GW implementation in the yambo code using both the Godby–Needs plasmon-pole model (GN-PPA) and the recently introduced multipole approximation (MPA). Quasiparticle energies are compared against GW100 reference data to evaluate the performance, numerical stability, and consistency of these approaches. Our results show that the GN-PPA approach is in very good agreement with full-frequency methods, further improved by the excellent agreement of the MPA scheme, especially when comparing with plane-wave codes.

• Båtnes, Maria; Leon, Dario A.; Larsbo, Mats & Eich-Greatorex, Susanne (2026). Subsoil structural and hydraulic responses to reconstruction and crushed shale amendment under contrasting crop management. Soil & Tillage Research. ISSN 0167-1987. 265. doi: 10.1016/j.still.2026.107433. Fulltekst i vitenarkiv Vis sammendrag

  Soil reconstruction using excavated materials is increasingly considered a sustainable strategy for restoring agricultural land, yet its success depends on the development of suitable subsoil physical and chemical conditions. This study evaluated early physical, hydraulic, chemical, and agronomic responses of a reconstructed loamy Stagnosol with and without crushed shale amendment, compared with an undisturbed reference, under four contrasting crop management systems. Soil water retention, pore size distributions derived from fitted retention functions, bulk density, air-filled porosity, and chemical properties were assessed over two growing seasons, while grain yields were monitored for three years. Shale amendment substantially altered subsoil properties relative to reconstruction alone. A bimodal retention model was required to adequately describe shale-amended subsoils, and the derived pore size distributions showed a distinct secondary peak in the macropore domain, and reduced contributions from micro- and mesopores. These changes were accompanied by higher air-filled porosity and lower plant available water. Shale amendment also increased subsoil pH and the availability of Ca and Mg. In contrast, reconstruction without shale caused mainly transient changes in bulk density, with differences no longer detectable after two growing seasons, and had comparably small effects on water retention. Crop management effects were largely confined to the topsoil and produced no clear changes in subsoil properties during the study period. Despite lower plant available water, shale-amended soils tended to produce higher grain yields throughout the experiment, with the clearest differences emerging in the third growing season. The results show that crushed shale redistributed pore volume and altered the chemical properties of reconstructed subsoils during the early years following reconstruction. Amendment selection should therefore consider potential trade-offs among aeration, water retention, nutrient availability, and crop performance when designing reconstructed agricultural soils.

• Leon, Dario A.; Cardoso, Claudia & Berland, Kristian (2026). Bulk plasmons in elemental metals. Physical review B (PRB). ISSN 2469-9950. 113(12). doi: 10.1103/w51n-p91p. Fulltekst i vitenarkiv
• Leon, Dario A & Berland, Kristian (2026). Momentum- and frequency-resolved collective electronic excitations in solids: insights from spectroscopy and first-principles calculations. Journal of Physics: Condensed Matter. ISSN 0953-8984. 38(18), s. 183001–183001. doi: 10.1088/1361-648x/ae62e7. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Collective electronic excitations, including plasmons, excitons, and intra- and interband transitions, play a central role in determining the dynamic screening, optical response, and energy transport properties of materials. Recent advances in momentum- and frequency-resolved spectroscopies, such as electron energy-loss spectroscopy and inelastic x-ray scattering, together with progress in first-principles many-body perturbation theory calculations, now allow collective excitations to be mapped with considerable precision across the Brillouin zone. This topical review surveys current developments in the representation and interpretation of both experimental and theoretical dielectric-response spectra. Particular emphasis is placed on recent ways of representing spectral band structures of the direct and inverse dielectric functions, such as analytical approaches based on multipole-Padé approximants in momentum and frequency (MPA( q )), which provide a combined band-like description of the dispersion of the main collective excitations. We discuss how features observed in metals, semiconductors, and low dimensional systems reflect the interplay between electronic structure, screening strength, and local-field effects, and how post-processing procedures can improve the quantitative comparison between experiment and theory. Finally, we provide perspectives on open challenges and potential developments in quantitative dielectric-function analyses.

• Valido, Dario Alejandro Leon; Kuisma, Mikael; Sauer, Mikkel Ohm; Svaneborg, Jakob K.; Svendsen, Mark K. & Americo, Stefano [Vis alle 9 forfattere av denne artikkelen] (2025). Self-consistent layer-projected scissors operator for band structures of two-dimensional van der Waals materials with large unit cells. Physical review B (PRB). ISSN 2469-9950. 112(11). doi: https:/journals.aps.org/prb/abstract/10.1103/2y5s-qcw9. Fulltekst i vitenarkiv Vis sammendrag

  We introduce a computationally efficient method to calculate the quasiparticle band structure of general van der Waals (vdW) heterostructures. A layer-projected scissors (LAPS) operator, which depends on the one-body density matrix, is added to the density functional theory Hamiltonian. The LAPS operator corrects the band edges of the individual layers for self-energy effects (both intralayer and interlayer) and unphysical strain fields stemming from the use of model supercells. The LAPS operator is treated self-consistently whereby charge redistribution and interlayer hybridization occurring in response to the band energy corrections are properly accounted for. We present several examples illustrating both the qualitative and quantitative performance of the method, including MoS2 films with up to 20 layers, bilayer MoS2 in an electric field, lattice-matched MoS2/WS2 and MoSe2/WSe2 bilayers, and MoSe2/WS2 moiré structures. Our work opens the way for predictive modeling of electronic, optical, and topological properties of experimentally relevant vdW materials, including twisted homobilayers and incommensurate heterostructures.

• Valido, Dario Alejandro Leon; Berland, Kristian & Cardoso, Claudia (2025). Spectral properties from an efficient analytical representation of the GW self-energy within a multipole approximation. Physical review B (PRB). ISSN 2469-9950. 111(19). doi: 10.1103/PhysRevB.111.195147. Fulltekst i vitenarkiv Vis sammendrag

  We propose an efficient analytical representation of the frequency-dependent 𝐺⁡𝑊 self-energy Σ via a multipole approximation (MPA-Σ). The MPA self-energy model is interpolated from a small set of numerical evaluations of Σ in the complex frequency plane, similar to the MPA interpolation developed for the screened Coulomb interaction (MPA-𝑊) [D. A. Leon et al., Phys. Rev. B 104, 115157 (2021)]. Crucially, MPA-Σ enables a multipole representation for the interacting Green's function 𝐺 (MPA-𝐺) and, in turn, access to all the spectral properties, including quasiparticle energies (QP) and renormalization factors beyond the linearized QP equation. We validate the MPA-Σ and MPA-𝐺 approaches for a diverse set of systems: bulk Si, Na, and Cu, monolayer MoS2 , the NaCl ion pair, and the F2 molecule. We show that, just as for MPA-𝑊, an appropriate choice of frequency sampling in MPA-Σ is critical to guarantee computational efficiency and high accuracy. Moreover, the combined MPA-𝑊 and MPA-Σ scheme considerably reduces the cost of full-frequency self-energy calculations, especially for spectral band structures over a wide energy range.

• Guandalini, Alberto; Leon_Valido, Dario Alejandro; D'Amico, Pino; Cardoso, Claudia; Ferretti, Andrea & Rontani, Massimo [Vis alle 7 forfattere av denne artikkelen] (2024). Efficient GW calculations via interpolation of the screened interaction in momentum and frequency space: The case of graphene. Physical review B (PRB). ISSN 2469-9950. 109(7). doi: 10.1103/PhysRevB.109.075120. Fulltekst i vitenarkiv
• Valido, Dario Alejandro Leon; Elgvin, Cana; Nguyen, Phuong Dan; Prytz, Øystein; Hage, Fredrik Sydow & Berland, Kristian (2024). Unraveling many-body effects in ZnO: Combined study using momentum-resolved electron energy-loss spectroscopy and first-principles calculations. Physical review B (PRB). ISSN 2469-9950. 109(11). doi: 10.1103/PhysRevB.109.115153. Fulltekst i vitenarkiv Vis sammendrag

  We present a detailed study of the dielectric response of ZnO using a combination of low-loss momentum- resolved electron energy-loss spectroscopy (EELS) and first-principles calculations at several levels of theory, from the independent particle and the random phase approximation with different variants of density functional theory (DFT), including hybrid and DFT + U schemes; to the Bethe-Salpeter equation (BSE). We use a method based on the f -sum rule to obtain the momentum-resolved experimental loss function and absorption spectra from EELS measurements. We characterize the main features in the direct and inverse dielectric functions of ZnO and their dispersion, associating them to single-particle features in the electronic band structure, while highlighting the important role of many-body effects such as plasmons and excitons. We discuss different signatures of the high anisotropy in the response function of ZnO, including the symmetry of the excitonic wave functions.

• Gonzalez, Augusto; Leon_Valido, Dario Alejandro; Perera, Yasser & Perez, Rolando (2023). On the gene expression landscape of cancer. PLOS ONE. 18(2). doi: 10.1371/journal.pone.0277786. Fulltekst i vitenarkiv
• Leon_Valido, Dario Alejandro; Ferretti, Andrea; Varsano, Daniele; Molinari, Elisa & Cardoso, Claudia (2023). Efficient full frequency GW for metals using a multipole approach for the dielectric screening. Physical review B (PRB). ISSN 2469-9950. 107(15). doi: 10.1103/PhysRevB.107.155130. Fulltekst i vitenarkiv
• Herrero, Roberto; Valido, Dario Alejandro Leon & Gonzalez, Augusto (2022). A one-dimensional parameter-free model for carcinogenesis in gene expression space. Scientific Reports. 12. doi: 10.1038/s41598-022-08502-8. Fulltekst i vitenarkiv Vis sammendrag

  A small portion of a tissue defines a microstate in gene expression space. Mutations, epigenetic events or external factors cause microstate displacements which are modeled by combining small independent gene expression variations and large Levy jumps, resulting from the collective variations of a set of genes. The risk of cancer in a tissue is estimated as the microstate probability to transit from the normal to the tumor region in gene expression space. The formula coming from the contribution of large Levy jumps seems to provide a qualitatively correct description of the lifetime risk of cancer in 8 tissues, and reveals an interesting connection between the risk and the way the tissue is protected against infections.

• Leon, Dario A.; Ferretti, Andrea; Varsano, Daniele; Molinari, Elisa & Cardoso, Claudia (2022). Graphene decoupling through oxygen intercalation on Gr/Co and Gr/Co/Ir interfaces. PHYSICAL REVIEW MATERIALS. 6(6). doi: 10.1103/physrevmaterials.6.064004. Fulltekst i vitenarkiv
• Gonzalez, Augusto; Quintela, Frank; Valido, Dario Alejandro Leon; Bringas-Vega, Maria Luisa & Valdes-Sosa, Pedro A. (2022). Estimating the number of available states for normal and tumor tissues in gene expression space. Biophysical Reports. 2(2). doi: 10.1016/j.bpr.2022.100053. Fulltekst i vitenarkiv Vis sammendrag

  The topology of gene expression space for a set of 12 cancer types is studied by means of an entropy-like magnitude, which measures the volumes of the regions occupied by tumor and normal samples, i.e., the number of available states (genotypes) that can be classified as tumor-like or normal-like, respectively. Computations show that the number of available states is much greater for tumors than for normal tissues, suggesting the irreversibility of the progression to the tumor phase. The entropy is nearly constant for tumors, whereas it exhibits a higher variability in normal tissues, probably due to tissue differentiation. In addition, we show an interesting correlation between the fraction (tumor/normal) of available states and the overlap between the tumor and normal sample clouds, interpreted as a way of reducing the decay rate to the tumor phase in more ordered or structured tissues.

• Cardoso, Claudia; Avvisati, Giulia; Gargiani, Pierluigi; Sbroscia, Marco; Jagadeesh, Madan S. & Mariani, Carlo [Vis alle 10 forfattere av denne artikkelen] (2021). Magnetic response and electronic states of well defined Graphene/Fe/Ir(111) heterostructure. PHYSICAL REVIEW MATERIALS. 5(1). doi: 10.1103/physrevmaterials.5.014405. Fulltekst i vitenarkiv
• Pacilè, Daniela; Cardoso, Claudia; Avvisati, Giulia; Vobornik, Ivana; Mariani, Carlo & Leon, Dario A. [Vis alle 10 forfattere av denne artikkelen] (2021). Narrowing of d bands of FeCo layers intercalated under graphene. Applied Physics Letters. ISSN 0003-6951. 118(12). doi: 10.1063/5.0047266. Fulltekst i vitenarkiv Vis sammendrag

  We report on the electronic properties of an artificial system obtained by the intercalation of equiatomic FeCo layers under graphene grown on Ir(111). Upon intercalation, the FeCo film grows epitaxially on Ir(111), resulting in a lattice-mismatched system. By performing density functional theory calculations, we show that the intercalated FeCo layer leads to a pronounced corrugation of the graphene film. At the same time, the FeCo intercalated layers induce a clear transition from a nearly undisturbed to a strongly hybridized graphene π-band, as measured by angle-resolved photoemission spectroscopy. A comparison of experimental results with the computed band structure and the projected density of states unveils a spin-selective hybridization between the π band of graphene and FeCo-3d states. Our results demonstrate that the reduced dimensionality, as well as the hybridization within the FeCo layers, induces a narrowing and a clear splitting of Fe 3d-up and Fe 3d-down-spin bands of the confined FeCo layers with respect to bulk Fe and Co.

• Gonzalez, Augusto; Nieves, Joan; Valido, Dario Alejandro Leon; Vega, Maria Luisa Bringas & Sosa, Pedro Valdes (2021). Gene expression rearrangements denoting changes in the biological state. Scientific Reports. 11. doi: 10.1038/s41598-021-87764-0. Fulltekst i vitenarkiv Vis sammendrag

  In many situations, the gene expression signature is a unique marker of the biological state. We study the modification of the gene expression distribution function when the biological state of a system experiences a change. This change may be the result of a selective pressure, as in the Long Term Evolution Experiment with E. Coli populations, or the progression to Alzheimer disease in aged brains, or the progression from a normal tissue to the cancer state. The first two cases seem to belong to a class of transitions, where the initial and final states are relatively close to each other, and the distribution function for the differential expressions is short ranged, with a tail of only a few dozens of strongly varying genes. In the latter case, cancer, the initial and final states are far apart and separated by a low-fitness barrier. The distribution function shows a very heavy tail, with thousands of silenced and over-expressed genes. We characterize the biological states by means of their principal component representations, and the expression distribution functions by their maximal and minimal differential expression values and the exponents of the Pareto laws describing the tails.

• Valido, Dario Alejandro Leon & Gonzalez, Augusto (2021). Mutations as Levy flights. Scientific Reports. 11. doi: 10.1038/s41598-021-88012-1. Fulltekst i vitenarkiv Vis sammendrag

  Data from a long time evolution experiment with Escherichia Coli and from a large study on copy number variations in subjects with European ancestry are analyzed in order to argue that mutations can be described as Levy flights in the mutation space. These Levy flights have at least two components: random single-base substitutions and large DNA rearrangements. From the data, we get estimations for the time rates of both events and the size distribution function of large rearrangements.

• Leon, Dario A.; Cardoso, Claudia; Chiarotti, Tommaso; Varsano, Daniele; Molinari, Elisa & Ferretti, Andrea (2021). Frequency dependence in GW made simple using a multipole approximation. Physical review B (PRB). ISSN 2469-9950. 104(11). doi: 10.1103/physrevb.104.115157. Fulltekst i vitenarkiv
• Valido, Dario Alejandro Leon (2018). Modeling evolution in a Long Time Evolution Experiment with E. Coli. https://arxiv.org/archive/q-bio. Fulltekst i vitenarkiv
• Valido, Dario Alejandro Leon (2016). The anionic instability threshold in atoms. Revista Cubana de Física. ISSN 0253-9268. 33(2). Fulltekst i vitenarkiv
• Valido, Dario Alejandro Leon (2016). Modeling mutations in bacteria and human tissues. https://arxiv.org/archive/q-bio. doi: 10.48550/ARXIV.1607.02164. Fulltekst i vitenarkiv

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• Valido, Dario Alejandro Leon (2026). Bridging first-principle calculations and spectroscopy for predictive understanding of collective excitations and engineering quantum materials. doi: https:/www.ecoss2026.net/program. Fulltekst i vitenarkiv
• Sangalli, Davide; Reho, Riccardo; Alliati, Ignacio Martin; Cervantes-Villanueva, Jorge; Kučukalić, Ali Esquembre & Geirsson, Torsten [Vis alle 23 forfattere av denne artikkelen] (2026). Lumen. doi: 10.5281/ZENODO.20121197. Fulltekst i vitenarkiv
• Valido, Dario Alejandro Leon (2025). Spectral properties from an efficient analytical representation of the GW self-energy within a multipole approximation. Fulltekst i vitenarkiv
• Valido, Dario Alejandro Leon (2025). Spectral properties from an efficient analytical representation of the GW self-energy within a multipole approximation. Fulltekst i vitenarkiv
• Valido, Dario Alejandro Leon (2025). Spectral properties from an efficient analytical representation of the GW self-energy within a multipole approximation. Fulltekst i vitenarkiv
• Valido, Dario Alejandro Leon; Berland, Kristian & Cardoso, Claudia (2025). Bulk plasmons in elemental metals. http://arxiv.org/abs/cond-mat. doi: https:/arxiv.org/pdf/2510.07261. Fulltekst i vitenarkiv Vis sammendrag

  The spectral properties, momentum dispersion, and broadening of bulk plasmonic excitations of 25 elemental metals are studied from first principles calculations in the random-phase approximation. Spectral band structures are constructed from the resulting momentum- and frequency-dependent inverse dielectric function. We develop an effective analytical representation of the main collective excitations in the dielectric response, by extending our earlier model based on multipole-Pad´e approximants (MPA) to incorporate both momentum and frequency dependence. With this tool, we identify plasmonic quasiparticle dispersions exhibiting complex features, including non-parabolic energy and intensity dispersions, discontinuities due to anisotropy, and overlapping effects that lead to band crossings and anti-crossings. We also find good agreement between computed results and available experiments in the optical limit. The results for elemental metals establish a reference point that can guide both fundamental studies and practical applications in plasmonics and spectroscopy.

• Valido, Dario Alejandro Leon (2024). Unraveling many-body effects in ZnO: Combined study using momentum-resolved electron energy-loss spectroscopy and first-principles calculations. Fulltekst i vitenarkiv
• Valido, Dario Alejandro Leon (2024). Unraveling many-body effects in ZnO: Combined study using momentum-resolved electron energy-loss spectroscopy and first-principles calculations. Fulltekst i vitenarkiv
• Valido, Dario Alejandro Leon; Nieves, Joan; Herrero, Roberto; Quintela, Frank & Gonzalez, Augusto (2024). evolp: A repository for mutations and gene expression data. The Cuban Scientist. 4(2), s. 1–2. doi: https:/cubanscientist.org/pdf/4/2/TCS_2023_4_2_001.pdf. Fulltekst i vitenarkiv Vis sammendrag

  We present evolp, a repository with a set of tools for analyzing mutations and gene expression data. We discuss some examples of applications, already published elsewhere.

• Valido, Dario Alejandro Leon (2024). A tour of many-body theory for modelling excitons in van der Waals heterostructures. Fulltekst i vitenarkiv
• Leon_Valido, Dario Alejandro (2024). Unraveling many-body effects in ZnO: Combined study using momentum-resolved electron energy-loss spectroscopy and first-principles calculations. Fulltekst i vitenarkiv
• Leon_Valido, Dario Alejandro (2024). Unraveling many-body effects in ZnO: Combined study using momentum-resolved electron energy-loss spectroscopy and first-principles calculations. Fulltekst i vitenarkiv
• Valido, Dario Alejandro Leon (2023). Frequency dependence in GW: origin, modelling and practical implementations. Fulltekst i vitenarkiv
• Valido, Dario Alejandro Leon (2022). Efficient full frequency GW using a multipole approach for the dielectric screening. Fulltekst i vitenarkiv
• Valido, Dario Alejandro Leon (2022). Electronic properties of wide-band-gap semiconductors resolved by low energy q-EELS. Fulltekst i vitenarkiv
• Valido, Dario Alejandro Leon (2022). Many-body perturbation theory-based approaches to understand finite-momentum EELS spectra. Fulltekst i vitenarkiv
• Valido, Dario Alejandro Leon (2021). Computational spectroscopy of inhomogeneous materials by many-body perturbation theory: method developments and applications. University of Modena and Reggio Emilia. Fulltekst i vitenarkiv

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