Pub Date : 2024-03-28DOI: 10.1088/2516-1075/ad3592
Mario Motta, William Kirby, Ieva Liepuoniute, Kevin J Sung, Jeffrey Cohn, Antonio Mezzacapo, Katherine Klymko, Nam Nguyen, Nobuyuki Yoshioka, Julia E Rice
Quantum subspace methods (QSMs) are a class of quantum computing algorithms where the time-independent Schrödinger equation for a quantum system is projected onto a subspace of the underlying Hilbert space. This projection transforms the Schrödinger equation into an eigenvalue problem determined by measurements carried out on a quantum device. The eigenvalue problem is then solved on a classical computer, yielding approximations to ground- and excited-state energies and wavefunctions. QSMs are examples of hybrid quantum–classical methods, where a quantum device supported by classical computational resources is employed to tackle a problem. QSMs are rapidly gaining traction as a strategy to simulate electronic wavefunctions on quantum computers, and thus their design, development, and application is a key research field at the interface between quantum computation and electronic structure (ES). In this review, we provide a self-contained introduction to QSMs, with emphasis on their application to the ES of molecules. We present the theoretical foundations and applications of QSMs, and we discuss their implementation on quantum hardware, illustrating the impact of noise on their performance.
{"title":"Subspace methods for electronic structure simulations on quantum computers","authors":"Mario Motta, William Kirby, Ieva Liepuoniute, Kevin J Sung, Jeffrey Cohn, Antonio Mezzacapo, Katherine Klymko, Nam Nguyen, Nobuyuki Yoshioka, Julia E Rice","doi":"10.1088/2516-1075/ad3592","DOIUrl":"https://doi.org/10.1088/2516-1075/ad3592","url":null,"abstract":"Quantum subspace methods (QSMs) are a class of quantum computing algorithms where the time-independent Schrödinger equation for a quantum system is projected onto a subspace of the underlying Hilbert space. This projection transforms the Schrödinger equation into an eigenvalue problem determined by measurements carried out on a quantum device. The eigenvalue problem is then solved on a classical computer, yielding approximations to ground- and excited-state energies and wavefunctions. QSMs are examples of hybrid quantum–classical methods, where a quantum device supported by classical computational resources is employed to tackle a problem. QSMs are rapidly gaining traction as a strategy to simulate electronic wavefunctions on quantum computers, and thus their design, development, and application is a key research field at the interface between quantum computation and electronic structure (ES). In this review, we provide a self-contained introduction to QSMs, with emphasis on their application to the ES of molecules. We present the theoretical foundations and applications of QSMs, and we discuss their implementation on quantum hardware, illustrating the impact of noise on their performance.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"59 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140584849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-18DOI: 10.1088/2516-1075/ad3124
Daniel Mejia-Rodriguez
The GW approximation has become an important tool for predicting charged excitations of isolated molecules and condensed systems. Its popularity can be attributed to many factors, including a favorable scaling and relatively good accuracy. In practical applications, the GW is often performed as a one-shot perturbation known as G0W0. Unfortunately, G0W0 suffers from a strong starting point dependence and is often not as accurate as one would need. Self-consistent GW methodologies alleviate these problems but come with a marked increase in computational cost. In this manuscript, we propose the use of an estimate of the exchange-correlation derivative discontinuity to provide a remarkably good starting point for G0W0 calculations, yielding ionization potentials and electron affinities with eigenvalue self-consistent GW quality at no additional cost. We assess the quality of the resulting methodology with the GW100 benchmark set and compare its advantages over other similar methods.
{"title":"Exploiting a derivative discontinuity estimate for accurate G0W0 ionization potentials and electron affinities","authors":"Daniel Mejia-Rodriguez","doi":"10.1088/2516-1075/ad3124","DOIUrl":"https://doi.org/10.1088/2516-1075/ad3124","url":null,"abstract":"The <italic toggle=\"yes\">GW</italic> approximation has become an important tool for predicting charged excitations of isolated molecules and condensed systems. Its popularity can be attributed to many factors, including a favorable scaling and relatively good accuracy. In practical applications, the <italic toggle=\"yes\">GW</italic> is often performed as a one-shot perturbation known as <inline-formula>\u0000<tex-math><?CDATA $G_0W_0$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msub><mml:mi>G</mml:mi><mml:mn>0</mml:mn></mml:msub><mml:msub><mml:mi>W</mml:mi><mml:mn>0</mml:mn></mml:msub></mml:math>\u0000<inline-graphic xlink:href=\"estad3124ieqn2.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>. Unfortunately, <inline-formula>\u0000<tex-math><?CDATA $G_0W_0$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msub><mml:mi>G</mml:mi><mml:mn>0</mml:mn></mml:msub><mml:msub><mml:mi>W</mml:mi><mml:mn>0</mml:mn></mml:msub></mml:math>\u0000<inline-graphic xlink:href=\"estad3124ieqn3.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> suffers from a strong starting point dependence and is often not as accurate as one would need. Self-consistent <italic toggle=\"yes\">GW</italic> methodologies alleviate these problems but come with a marked increase in computational cost. In this manuscript, we propose the use of an estimate of the exchange-correlation derivative discontinuity to provide a remarkably good starting point for <inline-formula>\u0000<tex-math><?CDATA $G_0W_0$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msub><mml:mi>G</mml:mi><mml:mn>0</mml:mn></mml:msub><mml:msub><mml:mi>W</mml:mi><mml:mn>0</mml:mn></mml:msub></mml:math>\u0000<inline-graphic xlink:href=\"estad3124ieqn4.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> calculations, yielding ionization potentials and electron affinities with eigenvalue self-consistent <italic toggle=\"yes\">GW</italic> quality at no additional cost. We assess the quality of the resulting methodology with the <italic toggle=\"yes\">GW</italic>100 benchmark set and compare its advantages over other similar methods.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"46 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140315117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-15DOI: 10.1088/2516-1075/ad2eb0
David M Ceperley, Scott Jensen, Yubo Yang, Hongwei Niu, Carlo Pierleoni, Markus Holzmann
Quantum Monte Carlo (QMC) can play a very important role in generating accurate data needed for constructing potential energy surfaces. We argue that QMC has advantages in terms of a smaller systematic bias and an ability to cover phase space more completely. The stochastic noise can ease the training of the machine learning model. We discuss how stochastic errors affect the generation of effective models by analyzing the errors within a linear least squares procedure, finding that there is an advantage to having many relatively imprecise data points for constructing models. We then analyze the effect of noise on a model of many-body silicon finding that noise in some situations improves the resulting model. We then study the effect of QMC noise on two machine learning models of dense hydrogen used in a recent study of its phase diagram. The noise enables us to estimate the errors in the model. We conclude with a discussion of future research problems.
{"title":"Training models using forces computed by stochastic electronic structure methods","authors":"David M Ceperley, Scott Jensen, Yubo Yang, Hongwei Niu, Carlo Pierleoni, Markus Holzmann","doi":"10.1088/2516-1075/ad2eb0","DOIUrl":"https://doi.org/10.1088/2516-1075/ad2eb0","url":null,"abstract":"Quantum Monte Carlo (QMC) can play a very important role in generating accurate data needed for constructing potential energy surfaces. We argue that QMC has advantages in terms of a smaller systematic bias and an ability to cover phase space more completely. The stochastic noise can ease the training of the machine learning model. We discuss how stochastic errors affect the generation of effective models by analyzing the errors within a linear least squares procedure, finding that there is an advantage to having many relatively imprecise data points for constructing models. We then analyze the effect of noise on a model of many-body silicon finding that noise in some situations improves the resulting model. We then study the effect of QMC noise on two machine learning models of dense hydrogen used in a recent study of its phase diagram. The noise enables us to estimate the errors in the model. We conclude with a discussion of future research problems.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"6 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140315409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-07DOI: 10.1088/2516-1075/ad29ab
A D N James, M Aichhorn, J Laverock
The last few decades has seen the rapid growth of interest in the bulk perovskite-type transition metal oxides SrVO<sub>3</sub> and SrTiO<sub>3</sub>. The electronic configuration of these perovskites differs by one electron associated to the transition metal species which gives rise to the drastically different electronic properties. Therefore, it is natural to look into how the electronic structure transitions between these bulk structures by using doping. Measurements of the substitutional doped SrTi<inline-formula> <tex-math><?CDATA $_{{1-x}}$?></tex-math> <mml:math overflow="scroll"><mml:msub><mml:mi> </mml:mi><mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:mrow></mml:msub></mml:math> <inline-graphic xlink:href="estad29abieqn3.gif" xlink:type="simple"></inline-graphic> </inline-formula>V<inline-formula> <tex-math><?CDATA $_{{{x}}}$?></tex-math> <mml:math overflow="scroll"><mml:msub><mml:mi></mml:mi><mml:mrow><mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:mrow></mml:mrow></mml:msub></mml:math> <inline-graphic xlink:href="estad29abieqn4.gif" xlink:type="simple"></inline-graphic> </inline-formula>O<sub>3</sub> shows an metal–insulator transition (MIT) as a function of doping. By using supercell density functional theory with dynamical mean field theory (DFT+DMFT), we show that the MIT is indeed the result of the combination of local electron correlation effects (Mott physics) within the <inline-formula> <tex-math><?CDATA $t_{{mathrm{2g}}}$?></tex-math> <mml:math overflow="scroll"><mml:msub><mml:mi>t</mml:mi><mml:mrow><mml:mrow><mml:mrow><mml:mn>2</mml:mn><mml:mi mathvariant="normal">g</mml:mi></mml:mrow></mml:mrow></mml:mrow></mml:msub></mml:math> <inline-graphic xlink:href="estad29abieqn5.gif" xlink:type="simple"></inline-graphic> </inline-formula> orbitals and the atomic site configuration of the transition metals which may indicate dependence on site disorder. SrTi<inline-formula> <tex-math><?CDATA $_{{1-x}}$?></tex-math> <mml:math overflow="scroll"><mml:msub><mml:mi> </mml:mi><mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:mrow></mml:msub></mml:math> <inline-graphic xlink:href="estad29abieqn6.gif" xlink:type="simple"></inline-graphic> </inline-formula>V<inline-formula> <tex-math><?CDATA $_{{{x}}}$?></tex-math> <mml:math overflow="scroll"><mml:msub><mml:mi></mml:mi><mml:mrow><mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:mrow></mml:mrow></mml:msub></mml:math> <inline-graphic xlink:href="estad29abieqn7.gif" xlink:type="simple"></inline-graphic> </inline-formula>O<sub>3</sub> may be an ideal candidate for benchmarking cutting-edge Mott–Anderson models of real systems. We show that applying an effective external perturbation on SrTi<inline-formula> <tex-math><?CDATA $_{{1-x}}$?></tex-math> <mml:math overflow="scroll"><mml:msub><mml:mi> </mml:mi><mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:mrow></mml
{"title":"Composition-driven Mott transition within SrTi 1−x V x O3","authors":"A D N James, M Aichhorn, J Laverock","doi":"10.1088/2516-1075/ad29ab","DOIUrl":"https://doi.org/10.1088/2516-1075/ad29ab","url":null,"abstract":"The last few decades has seen the rapid growth of interest in the bulk perovskite-type transition metal oxides SrVO<sub>3</sub> and SrTiO<sub>3</sub>. The electronic configuration of these perovskites differs by one electron associated to the transition metal species which gives rise to the drastically different electronic properties. Therefore, it is natural to look into how the electronic structure transitions between these bulk structures by using doping. Measurements of the substitutional doped SrTi<inline-formula>\u0000<tex-math><?CDATA $_{{1-x}}$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msub><mml:mi> </mml:mi><mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:mrow></mml:msub></mml:math>\u0000<inline-graphic xlink:href=\"estad29abieqn3.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>V<inline-formula>\u0000<tex-math><?CDATA $_{{{x}}}$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msub><mml:mi></mml:mi><mml:mrow><mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:mrow></mml:mrow></mml:msub></mml:math>\u0000<inline-graphic xlink:href=\"estad29abieqn4.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>O<sub>3</sub> shows an metal–insulator transition (MIT) as a function of doping. By using supercell density functional theory with dynamical mean field theory (DFT+DMFT), we show that the MIT is indeed the result of the combination of local electron correlation effects (Mott physics) within the <inline-formula>\u0000<tex-math><?CDATA $t_{{mathrm{2g}}}$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msub><mml:mi>t</mml:mi><mml:mrow><mml:mrow><mml:mrow><mml:mn>2</mml:mn><mml:mi mathvariant=\"normal\">g</mml:mi></mml:mrow></mml:mrow></mml:mrow></mml:msub></mml:math>\u0000<inline-graphic xlink:href=\"estad29abieqn5.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> orbitals and the atomic site configuration of the transition metals which may indicate dependence on site disorder. SrTi<inline-formula>\u0000<tex-math><?CDATA $_{{1-x}}$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msub><mml:mi> </mml:mi><mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:mrow></mml:msub></mml:math>\u0000<inline-graphic xlink:href=\"estad29abieqn6.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>V<inline-formula>\u0000<tex-math><?CDATA $_{{{x}}}$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msub><mml:mi></mml:mi><mml:mrow><mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:mrow></mml:mrow></mml:msub></mml:math>\u0000<inline-graphic xlink:href=\"estad29abieqn7.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>O<sub>3</sub> may be an ideal candidate for benchmarking cutting-edge Mott–Anderson models of real systems. We show that applying an effective external perturbation on SrTi<inline-formula>\u0000<tex-math><?CDATA $_{{1-x}}$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msub><mml:mi> </mml:mi><mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:mrow></mml","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"62 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140315099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-23DOI: 10.1088/2516-1075/ad28f1
Loris Delafosse, Amr Hussein, Saad Yalouz, Vincent Robert
Perturbative methods are attractive to describe the electronic structure of molecular systems because of their low-computational cost and systematically improvable character. In this work, a two-step perturbative approach is introduced combining multi-state Rayleigh-Schrödinger (effective Hamiltonian theory) and state-specific Brillouin-Wigner schemes to treat degenerate configurations and yield an efficient evaluation of multiple energies. The first step produces model functions and an updated definition of the perturbative partitioning of the Hamiltonian. The second step inherits the improved starting point provided in the first step, enabling then faster processing of the perturbative corrections for each individual state. The here-proposed two-step method is exemplified on a model-Hamiltonian of increasing complexity.
{"title":"A two-step Rayleigh-Schrödinger Brillouin-Wigner approach to transition energies","authors":"Loris Delafosse, Amr Hussein, Saad Yalouz, Vincent Robert","doi":"10.1088/2516-1075/ad28f1","DOIUrl":"https://doi.org/10.1088/2516-1075/ad28f1","url":null,"abstract":"Perturbative methods are attractive to describe the electronic structure of molecular systems because of their low-computational cost and systematically improvable character. In this work, a two-step perturbative approach is introduced combining multi-state Rayleigh-Schrödinger (effective Hamiltonian theory) and state-specific Brillouin-Wigner schemes to treat degenerate configurations and yield an efficient evaluation of multiple energies. The first step produces model functions and an updated definition of the perturbative partitioning of the Hamiltonian. The second step inherits the improved starting point provided in the first step, enabling then faster processing of the perturbative corrections for each individual state. The here-proposed two-step method is exemplified on a model-Hamiltonian of increasing complexity.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"69 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140004360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-01DOI: 10.1088/2516-1075/ad1e3b
Bo Peng, Karol Kowalski
In this study, we introduce a novel approach to coupled-cluster Green’s function (CCGF) embedding by seamlessly integrating conventional CCGF theory with the state-of-the-art sub-system embedding sub-algebras coupled cluster (SES-CC) formalism. This integration focuses primarily on delineating the characteristics of the sub-system and the corresponding segments of the Green’s function, defined explicitly by active orbitals. Crucially, our work involves the adaptation of the SES-CC paradigm, addressing the left eigenvalue problem through a distinct form of Hamiltonian similarity transformation. This advancement not only facilitates a comprehensive representation of the interaction between the embedded sub-system and its surrounding environment but also paves the way for the quantum mechanical description of multiple embedded domains, particularly by employing the emergent quantum flow algorithms. Our theoretical underpinnings further set the stage for a generalization to multiple embedded sub-systems. This expansion holds significant promise for the exploration and application of non-equilibrium quantum systems, enhancing the understanding of system–environment interactions. In doing so, the research underscores the potential of SES-CC embedding within the realm of quantum computations and multi-scale simulations, promising a good balance between accuracy and computational efficiency.
{"title":"Integrating subsystem embedding subalgebras and coupled cluster Green’s function: a theoretical foundation for quantum embedding in excitation manifold","authors":"Bo Peng, Karol Kowalski","doi":"10.1088/2516-1075/ad1e3b","DOIUrl":"https://doi.org/10.1088/2516-1075/ad1e3b","url":null,"abstract":"In this study, we introduce a novel approach to coupled-cluster Green’s function (CCGF) embedding by seamlessly integrating conventional CCGF theory with the state-of-the-art sub-system embedding sub-algebras coupled cluster (SES-CC) formalism. This integration focuses primarily on delineating the characteristics of the sub-system and the corresponding segments of the Green’s function, defined explicitly by active orbitals. Crucially, our work involves the adaptation of the SES-CC paradigm, addressing the left eigenvalue problem through a distinct form of Hamiltonian similarity transformation. This advancement not only facilitates a comprehensive representation of the interaction between the embedded sub-system and its surrounding environment but also paves the way for the quantum mechanical description of multiple embedded domains, particularly by employing the emergent quantum flow algorithms. Our theoretical underpinnings further set the stage for a generalization to multiple embedded sub-systems. This expansion holds significant promise for the exploration and application of non-equilibrium quantum systems, enhancing the understanding of system–environment interactions. In doing so, the research underscores the potential of SES-CC embedding within the realm of quantum computations and multi-scale simulations, promising a good balance between accuracy and computational efficiency.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"92 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139756148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-04DOI: 10.1088/2516-1075/ad1614
Christian-Roman Gerhorst, Alexander Neukirchen, Daniel A Klüppelberg, Gustav Bihlmayer, Markus Betzinger, Gregor Michalicek, Daniel Wortmann, Stefan Blügel
Phonons are quantized vibrations of a crystal lattice that play a crucial role in understanding many properties of solids. Density functional theory provides a state-of-the-art computational approach to lattice vibrations from first-principles. We present a successful software implementation for calculating phonons in the harmonic approximation, employing density-functional perturbation theory within the framework of the full-potential linearized augmented plane-wave method as implemented in the electronic structure package FLEUR. The implementation, which involves the Sternheimer equation for the linear response of the wave function, charge density, and potential with respect to infinitesimal atomic displacements, as well as the setup of the dynamical matrix, is presented and the specifics due to the muffin-tin sphere centered linearized augmented plane-wave basis-set and the all-electron nature are discussed. As a test, we calculate the phonon dispersion of several solids including an insulator, a semiconductor as well as several metals. The latter are comprised of magnetic, simple, and transition metals. The results are validated on the basis of phonon dispersions calculated using the finite displacement approach in conjunction with the FLEUR code and the phonopy package, as well as by some experimental results. An excellent agreement is obtained.
{"title":"Phonons from density-functional perturbation theory using the all-electron full-potential linearized augmented plane-wave method FLEUR * * Dedicated to the memory of Henry Krakauer (1947–2023).","authors":"Christian-Roman Gerhorst, Alexander Neukirchen, Daniel A Klüppelberg, Gustav Bihlmayer, Markus Betzinger, Gregor Michalicek, Daniel Wortmann, Stefan Blügel","doi":"10.1088/2516-1075/ad1614","DOIUrl":"https://doi.org/10.1088/2516-1075/ad1614","url":null,"abstract":"Phonons are quantized vibrations of a crystal lattice that play a crucial role in understanding many properties of solids. Density functional theory provides a state-of-the-art computational approach to lattice vibrations from first-principles. We present a successful software implementation for calculating phonons in the harmonic approximation, employing density-functional perturbation theory within the framework of the full-potential linearized augmented plane-wave method as implemented in the electronic structure package <monospace>FLEUR</monospace>. The implementation, which involves the Sternheimer equation for the linear response of the wave function, charge density, and potential with respect to infinitesimal atomic displacements, as well as the setup of the dynamical matrix, is presented and the specifics due to the muffin-tin sphere centered linearized augmented plane-wave basis-set and the all-electron nature are discussed. As a test, we calculate the phonon dispersion of several solids including an insulator, a semiconductor as well as several metals. The latter are comprised of magnetic, simple, and transition metals. The results are validated on the basis of phonon dispersions calculated using the finite displacement approach in conjunction with the <monospace>FLEUR</monospace> code and the <monospace>phonopy</monospace> package, as well as by some experimental results. An excellent agreement is obtained.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"116 9-10 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139092384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-21DOI: 10.1088/2516-1075/ad17d5
A. Es-smairi, N. Fazouan, E. Maskar, Ibrahim Bziz, Mohammed Sabil, Ayan Banik, D. P. Rai
In this current study, we used the density functional theory (DFT) method to examine the physical properties of ZnS nanosheets doped with Tm, Y, Gd, and Eu at a concentration of 6.25%. The non-magnetic phase is energetically stable when doped with Y and Tm. However, the ferromagnetic state is thermodynamically stable when doped with Eu and Gd with a negative formation energy value. The optimized structure is a planar structure for all doped systems, with an increase in the lattice parameter and bond length. On doping the Fermi level is pushed into the conduction band narrowing the band gap, and exhibiting typical n-type semiconducting behaviour. In a wider optical window, Tm and Y-doped systems have lower reflectance and more excellent transmittance than Gd and Eu-doped systems in the visible light spectrum. The electrical conductivity has been calculated using the BoltzTrap package. The electrical conductivity has been enhanced on doping suitable for its application in optoelectronic devices, solar cells, spintronics and thermoelectrics.
在本研究中，我们使用密度泛函理论（DFT）方法研究了掺杂了 Tm、Y、Gd 和 Eu（浓度为 6.25%）的 ZnS 纳米片的物理性质。当掺杂 Y 和 Tm 时，非磁性相在能量上是稳定的。然而，当掺杂 Eu 和 Gd 时，铁磁态在热力学上是稳定的，其形成能值为负。所有掺杂体系的优化结构都是平面结构，晶格参数和键长都有所增加。掺杂后，费米级被推向导带，缩小了带隙，表现出典型的 n 型半导体特性。在更宽的光学窗口中，与掺杂钆和铕的系统相比，掺杂锝和掺杂钇的系统在可见光光谱中具有更低的反射率和更出色的透射率。导电性是通过 BoltzTrap 软件包计算得出的。电导率在掺杂后得到增强，适合应用于光电器件、太阳能电池、自旋电子学和热电。
{"title":"Rare earth (Tm, Y, Gd, and Eu) doped ZnS monolayer: A comparative first-principles study.","authors":"A. Es-smairi, N. Fazouan, E. Maskar, Ibrahim Bziz, Mohammed Sabil, Ayan Banik, D. P. Rai","doi":"10.1088/2516-1075/ad17d5","DOIUrl":"https://doi.org/10.1088/2516-1075/ad17d5","url":null,"abstract":"\u0000 In this current study, we used the density functional theory (DFT) method to examine the physical properties of ZnS nanosheets doped with Tm, Y, Gd, and Eu at a concentration of 6.25%. The non-magnetic phase is energetically stable when doped with Y and Tm. However, the ferromagnetic state is thermodynamically stable when doped with Eu and Gd with a negative formation energy value. The optimized structure is a planar structure for all doped systems, with an increase in the lattice parameter and bond length. On doping the Fermi level is pushed into the conduction band narrowing the band gap, and exhibiting typical n-type semiconducting behaviour. In a wider optical window, Tm and Y-doped systems have lower reflectance and more excellent transmittance than Gd and Eu-doped systems in the visible light spectrum. The electrical conductivity has been calculated using the BoltzTrap package. The electrical conductivity has been enhanced on doping suitable for its application in optoelectronic devices, solar cells, spintronics and thermoelectrics.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"57 19","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138952180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-19DOI: 10.1088/2516-1075/ad16f4
P. Ding, Xiaoxiao Man, Qingxin Liu, Huan Ma, Bin Liu, Zhi Ren, Kai Liu, Shancai Wang
The layered material Sn4Sb3 exhibits superconductivity with T c∽1.47 K and is proposed to be a topological superconductor candidate. In this study, we investigate the electronic structure of Sn4Sb3 using angle-resolved photoemission spectroscopy and density functional theory (DFT) calculations. Despite its layered structure, the band structure of Sn4Sb3 shows strong k z dependence, leading to the formation of a three-dimensional Fermi surface. The electronic bands exhibit three-fold symmetry at most k z planes and six-fold symmetry at the Γ and Z planes. These observations are consistent with DFT calculations, except for the presence of additional flat-like bands located 500 meV below the Fermi level. The photon energy dependence measurement show noticeable k z dispersion in one of the splitted branches, suggesting a bulk origin of the feature, and negligible k z dispersion in another branch, implying the surface origin of the state.
层状材料 Sn4Sb3 具有 T c∽1.47 K 的超导性，被认为是拓扑超导体的候选材料。在本研究中，我们利用角度分辨光发射光谱和密度泛函理论（DFT）计算研究了Sn4Sb3的电子结构。尽管具有层状结构，但 Sn4Sb3 的能带结构显示出强烈的 k z 依赖性，从而形成了一个三维费米面。电子带在大多数 k z 平面上呈现三折对称性，而在Γ和 Z 平面上呈现六折对称性。这些观察结果与 DFT 计算结果一致，只是在费米水平以下 500 meV 存在额外的扁平带。光子能量依赖性测量结果表明，在其中一个分裂分支中存在明显的 k z 弥散，这表明该特征起源于体态，而在另一个分支中 k z 弥散可以忽略不计，这意味着该状态起源于表面。
{"title":"Three-dimensional electronic structure of the superconductor Sn4Sb3 by angle-resolved photoemission spectroscopy","authors":"P. Ding, Xiaoxiao Man, Qingxin Liu, Huan Ma, Bin Liu, Zhi Ren, Kai Liu, Shancai Wang","doi":"10.1088/2516-1075/ad16f4","DOIUrl":"https://doi.org/10.1088/2516-1075/ad16f4","url":null,"abstract":"\u0000 The layered material Sn4Sb3 exhibits superconductivity with T\u0000 c∽1.47 K and is proposed to be a topological superconductor candidate. In this study, we investigate the electronic structure of Sn4Sb3 using angle-resolved photoemission spectroscopy and density functional theory (DFT) calculations. Despite its layered structure, the band structure of Sn4Sb3 shows strong k\u0000 z dependence, leading to the formation of a three-dimensional Fermi surface. The electronic bands exhibit three-fold symmetry at most k\u0000 z planes and six-fold symmetry at the Γ and Z planes. These observations are consistent with DFT calculations, except for the presence of additional flat-like bands located 500 meV below the Fermi level. The photon energy dependence measurement show noticeable k\u0000 z dispersion in one of the splitted branches, suggesting a bulk origin of the feature, and negligible k\u0000 z dispersion in another branch, implying the surface origin of the state.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":" 81","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138962149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-14DOI: 10.1088/2516-1075/ad159f
Rodrigo E. Menchón, Iñigo Delgado Enales, D. Sánchez-Portal, A. Garcia-Lekue
On-surface synthesis of graphene nanoribbons (GNRs) enables engineering their electronic and magnetic properties, which sensitively depend on their precise bonding structure, morphology and chemical composition. Here, we investigate nitrogen and boron co-doping in order to better understand the effects of simultaneous chemical substitution in sites along the backbone of 7AGNRs. In a comparative analysis with the pristine system, the origin of the impurity bands that nitro-borylated systems exhibit was addresed. In addition to this, we studied the appearance of an electric dipolar moment, the charge transfer mechanism behind it and its dependence on the distance between BN centres. The high defect concentration limit and the dilute limit were investigated, along with various doping schemes with four substitutional doping sites and the possible emergence of magnetism in these systems.
{"title":"B and N substitutional co-doping in 7AGNRs","authors":"Rodrigo E. Menchón, Iñigo Delgado Enales, D. Sánchez-Portal, A. Garcia-Lekue","doi":"10.1088/2516-1075/ad159f","DOIUrl":"https://doi.org/10.1088/2516-1075/ad159f","url":null,"abstract":"\u0000 On-surface synthesis of graphene nanoribbons (GNRs) enables engineering their electronic and magnetic properties, which sensitively depend on their precise bonding structure, morphology and chemical composition. Here, we investigate nitrogen and boron co-doping in order to better understand the effects of simultaneous chemical substitution in sites along the backbone of 7AGNRs. In a comparative analysis with the pristine system, the origin of the impurity bands that nitro-borylated systems exhibit was addresed. In addition to this, we studied the appearance of an electric dipolar moment, the charge transfer mechanism behind it and its dependence on the distance between BN centres. The high defect concentration limit and the dilute limit were investigated, along with various doping schemes with four substitutional doping sites and the possible emergence of magnetism in these systems.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"46 2","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139003125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：