Pub Date : 2024-03-19DOI: 10.1088/2516-1075/ad3591
J. Rehr, J. Kas
The van der Waals (vdW) interaction between non-overlapping systems arises from long-range correlations in electronic systems due to the attraction between their coupled density fluctuations. Here we present a treatment based on a generalized real-space multiple-scattering approach which is applicable to both spherical and non-spherical geometries. The method is tested for the vdW interactions between two isolated atoms.
{"title":"Real-space multiple-scattering approach to the van der Waals interaction","authors":"J. Rehr, J. Kas","doi":"10.1088/2516-1075/ad3591","DOIUrl":"https://doi.org/10.1088/2516-1075/ad3591","url":null,"abstract":"\u0000 The van der Waals (vdW) interaction between non-overlapping systems arises from long-range correlations in electronic systems due to the attraction between their coupled density fluctuations. Here we present a treatment based on a generalized real-space multiple-scattering approach which is applicable to both spherical and non-spherical geometries. The method is tested for the vdW interactions between two isolated atoms.","PeriodicalId":502740,"journal":{"name":"Electronic Structure","volume":"70 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140229947","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 : 2024-03-14DOI: 10.1088/2516-1075/ad341e
Po-Hao Chang, Zachary Buschmann, R. Zope
The universal applicability of density functional approximations is limited by the self-interaction error made by these functionals. Recently, a novel one-electron self-interaction-correction (SIC) method that uses an iso-orbital indicator to apply the SIC at each point in space by scaling the exchange-correlation and Coulomb energy densities was proposed. The LSIC method is exact for the one-electron densities, and unlike the well-known Perdew-Zunger SIC (PZSIC) method recovers the uniform electron gas limit of the uncorrected density functional approximation and reduces to PZSIC method as a special case when the isoorbital indicator is set to unity. Here, we present a numerical scheme that we have adopted to evaluate the Coulomb potential of the electron density scaled by the iso-orbital indicator required for the self-consistent LSIC calculations. After analyzing the behavior of the finite difference method and the green function solution to the radial part of the Poisson equation, we adopt a hybrid approach that uses the FDM method for the Coulomb potential due to the monopole and the GF for all higher order terms. The performance of the resultant hybrid method is assessed using a variety of systems. The results show improved accuracy compared to earlier numerical schemes. We also find that, even with a generic set of radial grid parameters, accurate energy differences can be obtained using a numerical Coulomb solver in standard density functional studies.
{"title":"A numerical Poisson solver with improved radial solutions for a self-consistent locally scaled self-interaction correction method","authors":"Po-Hao Chang, Zachary Buschmann, R. Zope","doi":"10.1088/2516-1075/ad341e","DOIUrl":"https://doi.org/10.1088/2516-1075/ad341e","url":null,"abstract":"\u0000 The universal applicability of density functional approximations is limited by the self-interaction error made by these functionals. Recently, a novel one-electron self-interaction-correction (SIC) method that uses an iso-orbital indicator to apply the SIC at each point in space by scaling the exchange-correlation and Coulomb energy densities was proposed. The LSIC method is exact for the one-electron densities, and unlike the well-known Perdew-Zunger SIC (PZSIC) method recovers the uniform electron gas limit of the uncorrected density functional approximation and reduces to PZSIC method as a special case when the isoorbital indicator is set to unity. Here, we present a numerical scheme that we have adopted to evaluate the Coulomb potential of the electron density scaled by the iso-orbital indicator required for the self-consistent LSIC calculations. After analyzing the behavior of the finite difference method and the green function solution to the radial part of the Poisson equation, we adopt a hybrid approach that uses the FDM method for the Coulomb potential due to the monopole and the GF for all higher order terms. The performance of the resultant hybrid method is assessed using a variety of systems. The results show improved accuracy compared to earlier numerical schemes. We also find that, even with a generic set of radial grid parameters, accurate energy differences can be obtained using a numerical Coulomb solver in standard density functional studies.","PeriodicalId":502740,"journal":{"name":"Electronic Structure","volume":"8 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140243036","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/ad3123
Ashmita Biswas, Surajit Samui, R. Dey
The wordwide energy demands and the surge towards a net-zero sustainable society let the researchers set a goal towards the end of carbon cycle. This has enormously exaggerated the electrocatalytic processes such as water splitting, CO2 capture and reduction and nitrogen reduction reaction (NRR) as a safe and green alternative as these involve the utilization of renewable green power. Interestingly, the NH3 produced from NRR has been realized as a future fuel in terms of safer green H2 storage and transportation. Nevertheless, to scale up the NH3 production electrochemically, a benevolent catalyst needs to be developed. More interestingly, the electronic features of the catalyst that actually contribute to the interaction and binding between the adsorbate and reaction intermediates should be analyzed such that these can be tuned based on our requirements to obtain the desired high-standard goals of NH3 synthesis. The current topical review aims to provide an illustrative understanding on the experimental and theoretical descriptors that are likely to influence the electronic structure of catalysts for NRR. We have widely covered a detailed explanation regarding work function, d-band center and electronic effect on the electronic structures of the catalysts. While summarizing the same, we realized that there are several discrepancies in this field, which have not been discussed and could be misleading for the newcomers in the field. Thus, we have briefed the limitations and diverging explanations and have provided a few directions that could be looked upon to overcome the issues.
{"title":"Interlinking electronic band properties in catalysts with electrochemical nitrogen reduction performance: A direct influence","authors":"Ashmita Biswas, Surajit Samui, R. Dey","doi":"10.1088/2516-1075/ad3123","DOIUrl":"https://doi.org/10.1088/2516-1075/ad3123","url":null,"abstract":"\u0000 The wordwide energy demands and the surge towards a net-zero sustainable society let the researchers set a goal towards the end of carbon cycle. This has enormously exaggerated the electrocatalytic processes such as water splitting, CO2 capture and reduction and nitrogen reduction reaction (NRR) as a safe and green alternative as these involve the utilization of renewable green power. Interestingly, the NH3 produced from NRR has been realized as a future fuel in terms of safer green H2 storage and transportation. Nevertheless, to scale up the NH3 production electrochemically, a benevolent catalyst needs to be developed. More interestingly, the electronic features of the catalyst that actually contribute to the interaction and binding between the adsorbate and reaction intermediates should be analyzed such that these can be tuned based on our requirements to obtain the desired high-standard goals of NH3 synthesis. The current topical review aims to provide an illustrative understanding on the experimental and theoretical descriptors that are likely to influence the electronic structure of catalysts for NRR. We have widely covered a detailed explanation regarding work function, d-band center and electronic effect on the electronic structures of the catalysts. While summarizing the same, we realized that there are several discrepancies in this field, which have not been discussed and could be misleading for the newcomers in the field. Thus, we have briefed the limitations and diverging explanations and have provided a few directions that could be looked upon to overcome the issues.","PeriodicalId":502740,"journal":{"name":"Electronic Structure","volume":"34 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140258302","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 : 2024-02-06DOI: 10.1088/2516-1075/ad2693
Sarah Pak, Daniel R. Nascimento
Time-dependent density functional theory (TD-DFT) stands out as an efficient tool for computing core-level spectra in large molecules, particularly transition metal complexes. However, despite their relatively moderate computational demands, TD-DFT methods can still pose challenges for typical computations involving transition metal complexes with over a thousand basis functions. In this study, we investigate the role of the Coulomb, Hartree-Fock exchange, and exchange-correlation kernel contributions to the TD-DFT coupling matrix elements when simulating core-level spectra in transition metal complexes. Our observations reveal that the exchange-correlation kernel contribution, responsible for more than 50% of the computational time in a hybrid TD-DFT calculation, surprisingly has no discernible impact on the qualitative aspects of the calculated spectra. While the Coulomb term plays a crucial role in describing L2,3-edge spectra, its significance becomes negligible when considering K, L 1 , and M 4,5 edges. In contrast, the scaled Hartree-Fock exchange is demonstrated to be the most influential term, underscoring the necessity for hybrid density functional approximations in accurately simulating core-level spectra. These trends hold irrespective of the chosen basis set and exchange-correlation functional, providing valuable insights for the development of approximate methods for incorporating two-electron interactions within the realm of core-level spectroscopies.
{"title":"The role of the coupling matrix elements in time-dependent density functional theory on the simulation of core-level spectra of transition metal complexes","authors":"Sarah Pak, Daniel R. Nascimento","doi":"10.1088/2516-1075/ad2693","DOIUrl":"https://doi.org/10.1088/2516-1075/ad2693","url":null,"abstract":"\u0000 Time-dependent density functional theory (TD-DFT) stands out as an efficient tool for computing core-level spectra in large molecules, particularly transition metal complexes. However, despite their relatively moderate computational demands, TD-DFT methods can still pose challenges for typical computations involving transition metal complexes with over a thousand basis functions. In this study, we investigate the role of the Coulomb, Hartree-Fock exchange, and exchange-correlation kernel contributions to the TD-DFT coupling matrix elements when simulating core-level spectra in transition metal complexes. Our observations reveal that the exchange-correlation kernel contribution, responsible for more than 50% of the computational time in a hybrid TD-DFT calculation, surprisingly has no discernible impact on the qualitative aspects of the calculated spectra. While the Coulomb term plays a crucial role in describing L2,3-edge spectra, its significance becomes negligible when considering K, L 1 , and M 4,5 edges. In contrast, the scaled Hartree-Fock exchange is demonstrated to be the most influential term, underscoring the necessity for hybrid density functional approximations in accurately simulating core-level spectra. These trends hold irrespective of the chosen basis set and exchange-correlation functional, providing valuable insights for the development of approximate methods for incorporating two-electron interactions within the realm of core-level spectroscopies.","PeriodicalId":502740,"journal":{"name":"Electronic Structure","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139799946","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 : 2024-02-06DOI: 10.1088/2516-1075/ad2693
Sarah Pak, Daniel R. Nascimento
Time-dependent density functional theory (TD-DFT) stands out as an efficient tool for computing core-level spectra in large molecules, particularly transition metal complexes. However, despite their relatively moderate computational demands, TD-DFT methods can still pose challenges for typical computations involving transition metal complexes with over a thousand basis functions. In this study, we investigate the role of the Coulomb, Hartree-Fock exchange, and exchange-correlation kernel contributions to the TD-DFT coupling matrix elements when simulating core-level spectra in transition metal complexes. Our observations reveal that the exchange-correlation kernel contribution, responsible for more than 50% of the computational time in a hybrid TD-DFT calculation, surprisingly has no discernible impact on the qualitative aspects of the calculated spectra. While the Coulomb term plays a crucial role in describing L2,3-edge spectra, its significance becomes negligible when considering K, L 1 , and M 4,5 edges. In contrast, the scaled Hartree-Fock exchange is demonstrated to be the most influential term, underscoring the necessity for hybrid density functional approximations in accurately simulating core-level spectra. These trends hold irrespective of the chosen basis set and exchange-correlation functional, providing valuable insights for the development of approximate methods for incorporating two-electron interactions within the realm of core-level spectroscopies.
{"title":"The role of the coupling matrix elements in time-dependent density functional theory on the simulation of core-level spectra of transition metal complexes","authors":"Sarah Pak, Daniel R. Nascimento","doi":"10.1088/2516-1075/ad2693","DOIUrl":"https://doi.org/10.1088/2516-1075/ad2693","url":null,"abstract":"\u0000 Time-dependent density functional theory (TD-DFT) stands out as an efficient tool for computing core-level spectra in large molecules, particularly transition metal complexes. However, despite their relatively moderate computational demands, TD-DFT methods can still pose challenges for typical computations involving transition metal complexes with over a thousand basis functions. In this study, we investigate the role of the Coulomb, Hartree-Fock exchange, and exchange-correlation kernel contributions to the TD-DFT coupling matrix elements when simulating core-level spectra in transition metal complexes. Our observations reveal that the exchange-correlation kernel contribution, responsible for more than 50% of the computational time in a hybrid TD-DFT calculation, surprisingly has no discernible impact on the qualitative aspects of the calculated spectra. While the Coulomb term plays a crucial role in describing L2,3-edge spectra, its significance becomes negligible when considering K, L 1 , and M 4,5 edges. In contrast, the scaled Hartree-Fock exchange is demonstrated to be the most influential term, underscoring the necessity for hybrid density functional approximations in accurately simulating core-level spectra. These trends hold irrespective of the chosen basis set and exchange-correlation functional, providing valuable insights for the development of approximate methods for incorporating two-electron interactions within the realm of core-level spectroscopies.","PeriodicalId":502740,"journal":{"name":"Electronic Structure","volume":"33 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139859815","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 : 2024-02-02DOI: 10.1088/2516-1075/ad252b
J. Sau, Debanand Sa, Manoranjan Kumar
The Weyl points and nodal line emerge in the momentum space due to symmetry protected state in topological semimetal(TSM) materials and these materials hold significance due to their unusual anomalous transport properties. In this manuscript, we study the topological properties of the electronic band structure of a half-metallic ferromagnet Co$_{2}$FeSi employing the ab-initio DFT method and show that it is a strongly correlated material. The experimentally observed magnetic properties can be explained in terms of the Slater-Pauling (SP) rule and our calculations are consistent with it. We also investigate the band topology of Co$_{2}$FeSi and find that there are three topological nodal lines at 380 meV above Fermi Energy (textit{E$_F$}). The degeneracy of these nodal lines is perturbed upon introducing spin-orbit coupling with magnetization along [001] direction. However, some points still preserve degeneracy and are identified as Weyl points, each associated with a specific Chern number. At the ambient pressure, the AHC properties of this material have only extrinsic contribution which is consistent with the experimental results. To make the AHC intrinsic, we tune the position of the nodal line close to the Fermi energy by applying the hydrostatic pressure up to 26 GPa. We also discuss crystal symmetries and their relation with nodal lines and Weyl points.
{"title":"Hydrostatic Pressure-Induced Anomalous Hall Effect in Co$_{2}$FeSi Semimetal","authors":"J. Sau, Debanand Sa, Manoranjan Kumar","doi":"10.1088/2516-1075/ad252b","DOIUrl":"https://doi.org/10.1088/2516-1075/ad252b","url":null,"abstract":"\u0000 The Weyl points and nodal line emerge in the momentum space due to symmetry protected state in topological semimetal(TSM) materials and these materials hold significance due to their unusual anomalous transport properties. In this manuscript, we study the topological properties of the electronic band structure of a half-metallic ferromagnet Co$_{2}$FeSi employing the ab-initio DFT method and show that it is a strongly correlated material. The experimentally observed magnetic properties can be explained in terms of the Slater-Pauling (SP) rule and our calculations are consistent with it. We also investigate the band topology of Co$_{2}$FeSi and find that there are three topological nodal lines at 380 meV above Fermi Energy (textit{E$_F$}). The degeneracy of these nodal lines is perturbed upon introducing spin-orbit coupling with magnetization along [001] direction. However, some points still preserve degeneracy and are identified as Weyl points, each associated with a specific Chern number. At the ambient pressure, the AHC properties of this material have only extrinsic contribution which is consistent with the experimental results. To make the AHC intrinsic, we tune the position of the nodal line close to the Fermi energy by applying the hydrostatic pressure up to 26 GPa. We also discuss crystal symmetries and their relation with nodal lines and Weyl points.","PeriodicalId":502740,"journal":{"name":"Electronic Structure","volume":"101 1-2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139870670","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 : 2024-02-02DOI: 10.1088/2516-1075/ad252b
J. Sau, Debanand Sa, Manoranjan Kumar
The Weyl points and nodal line emerge in the momentum space due to symmetry protected state in topological semimetal(TSM) materials and these materials hold significance due to their unusual anomalous transport properties. In this manuscript, we study the topological properties of the electronic band structure of a half-metallic ferromagnet Co$_{2}$FeSi employing the ab-initio DFT method and show that it is a strongly correlated material. The experimentally observed magnetic properties can be explained in terms of the Slater-Pauling (SP) rule and our calculations are consistent with it. We also investigate the band topology of Co$_{2}$FeSi and find that there are three topological nodal lines at 380 meV above Fermi Energy (textit{E$_F$}). The degeneracy of these nodal lines is perturbed upon introducing spin-orbit coupling with magnetization along [001] direction. However, some points still preserve degeneracy and are identified as Weyl points, each associated with a specific Chern number. At the ambient pressure, the AHC properties of this material have only extrinsic contribution which is consistent with the experimental results. To make the AHC intrinsic, we tune the position of the nodal line close to the Fermi energy by applying the hydrostatic pressure up to 26 GPa. We also discuss crystal symmetries and their relation with nodal lines and Weyl points.
{"title":"Hydrostatic Pressure-Induced Anomalous Hall Effect in Co$_{2}$FeSi Semimetal","authors":"J. Sau, Debanand Sa, Manoranjan Kumar","doi":"10.1088/2516-1075/ad252b","DOIUrl":"https://doi.org/10.1088/2516-1075/ad252b","url":null,"abstract":"\u0000 The Weyl points and nodal line emerge in the momentum space due to symmetry protected state in topological semimetal(TSM) materials and these materials hold significance due to their unusual anomalous transport properties. In this manuscript, we study the topological properties of the electronic band structure of a half-metallic ferromagnet Co$_{2}$FeSi employing the ab-initio DFT method and show that it is a strongly correlated material. The experimentally observed magnetic properties can be explained in terms of the Slater-Pauling (SP) rule and our calculations are consistent with it. We also investigate the band topology of Co$_{2}$FeSi and find that there are three topological nodal lines at 380 meV above Fermi Energy (textit{E$_F$}). The degeneracy of these nodal lines is perturbed upon introducing spin-orbit coupling with magnetization along [001] direction. However, some points still preserve degeneracy and are identified as Weyl points, each associated with a specific Chern number. At the ambient pressure, the AHC properties of this material have only extrinsic contribution which is consistent with the experimental results. To make the AHC intrinsic, we tune the position of the nodal line close to the Fermi energy by applying the hydrostatic pressure up to 26 GPa. We also discuss crystal symmetries and their relation with nodal lines and Weyl points.","PeriodicalId":502740,"journal":{"name":"Electronic Structure","volume":"96 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139810782","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 : 2024-01-19DOI: 10.1088/2516-1075/ad2090
Sibel Özcan, Aurelio Jesus Gallardo Caparros, B. Biel
This study explores the realm of two-dimensional Transition Metal Dichalcogenides (TMDs), examining some of the most prevalent defects. Employing Density Functional Theory (DFT), we scrutinize three common defect types across four extensively studied TMDs: MoS2, MoSe2, WS2, and WSe2. Our investigation spans the energetics of these defects, unveiling the most stable ones, and unraveling the alterations in structural and electronic properties induced by their presence. As a further step towards practical applications, we simulate the images that would be captured by both Atomic and Kelvin Probe Force Microscopes, aiming at a facile identification of these defects when probed at the microscopic level.
{"title":"Point-like vacancies in Two-Dimensional Transition Metal Dichalcogenides","authors":"Sibel Özcan, Aurelio Jesus Gallardo Caparros, B. Biel","doi":"10.1088/2516-1075/ad2090","DOIUrl":"https://doi.org/10.1088/2516-1075/ad2090","url":null,"abstract":"\u0000 This study explores the realm of two-dimensional Transition Metal Dichalcogenides (TMDs), examining some of the most prevalent defects. Employing Density Functional Theory (DFT), we scrutinize three common defect types across four extensively studied TMDs: MoS2, MoSe2, WS2, and WSe2. Our investigation spans the energetics of these defects, unveiling the most stable ones, and unraveling the alterations in structural and electronic properties induced by their presence. As a further step towards practical applications, we simulate the images that would be captured by both Atomic and Kelvin Probe Force Microscopes, aiming at a facile identification of these defects when probed at the microscopic level.","PeriodicalId":502740,"journal":{"name":"Electronic Structure","volume":"5 33","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139525524","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 : 2024-01-18DOI: 10.1088/2516-1075/ad2004
DR Neetik Mukherjee, Gaurav Shukla, Ashwani Kumar Tiwari
Superhard materials with conductive properties are extremely important. They have potential applications in multifunctional devices under extreme natural conditions. Here we present a superhard and conductive sp$^{2}$-sp$^{3}$ mixed hybrid carbon allotrope through Density functional theory calculations. The proposed carbon phase contains 36 atoms in an orthorhombic unit cell with emph{Pmmm} symmetry. In present structure (namely poC$_{36}$), the sp$^{2}$ bonds are wrapped around inside the sp$^{3}$ bonded network. At 0 GPa it is dynamically stable and energetically more favourable than fullerene C$_{60}$, graphene, Orth-C$_{10}$, orth-C$^{`}_{10}$, oC$_{36}$, C$_{48}$, C20-sc, C21-sc, M-carbon, W-carbon etc. At 47.2 GPa pressure it's energy becomes lower than graphite. The Vickers hardness value is 76.32 GPa, which is higher than cubic boron nitride, the second hardest material. At 0 GPa it is an indirect band gap semi-conductor with band gap 0.08 eV. At around 11 GPa pressure, the valence band crosses the conduction band generating 1-D conductivity in poC$_{36}$. These, interesting features make poC$_{36}$ a useful material for mechanical tools and electronic devices. The Raman spectra exhibits a diamond-like band, alongside graphite-like G and D bands, all of which undergo rightward shifts with increasing pressure, indicating structural changes. X-ray diffraction at 0 GPa resembles diamond, but at 47 GPa, four peaks vanish while six new ones emerge, signifying significant structural alterations under high pressure.
{"title":"A superhard sp$^{2}$-sp$^{3}$ hybridized orthorhombic carbon allotrope with conductive property under extreme pressure","authors":"DR Neetik Mukherjee, Gaurav Shukla, Ashwani Kumar Tiwari","doi":"10.1088/2516-1075/ad2004","DOIUrl":"https://doi.org/10.1088/2516-1075/ad2004","url":null,"abstract":"\u0000 Superhard materials with conductive properties are extremely important. They have potential applications in multifunctional devices under extreme natural conditions. Here we present a superhard and conductive sp$^{2}$-sp$^{3}$ mixed hybrid carbon allotrope through Density functional theory calculations. The proposed carbon phase contains 36 atoms in an orthorhombic unit cell with emph{Pmmm} symmetry. In present structure (namely poC$_{36}$), the sp$^{2}$ bonds are wrapped around inside the sp$^{3}$ bonded network. At 0 GPa it is dynamically stable and energetically more favourable than fullerene C$_{60}$, graphene, Orth-C$_{10}$, orth-C$^{`}_{10}$, oC$_{36}$, C$_{48}$, C20-sc, C21-sc, M-carbon, W-carbon etc. At 47.2 GPa pressure it's energy becomes lower than graphite. The Vickers hardness value is 76.32 GPa, which is higher than cubic boron nitride, the second hardest material. At 0 GPa it is an indirect band gap semi-conductor with band gap 0.08 eV. At around 11 GPa pressure, the valence band crosses the conduction band generating 1-D conductivity in poC$_{36}$. These, interesting features make poC$_{36}$ a useful material for mechanical tools and electronic devices. The Raman spectra exhibits a diamond-like band, alongside graphite-like G and D bands, all of which undergo rightward shifts with increasing pressure, indicating structural changes. X-ray diffraction at 0 GPa resembles diamond, but at 47 GPa, four peaks vanish while six new ones emerge, signifying significant structural alterations under high pressure.","PeriodicalId":502740,"journal":{"name":"Electronic Structure","volume":"117 51","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139614192","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 : 2024-01-13DOI: 10.1088/2516-1075/ad2277
Jie Liu, Zhenyu Li, Jinlong Yang
Reducing circuit depth is essential for implementing quantum simulations of electronic structure on near-term quantum devices. In this work, we propose a variational quantum eigensolver (VQE) based perturbation theory algorithm to accurately simulate electron correlation of periodic materials with shallow ansatz circuits, which are generated from Adaptive Derivative-Assembled Pseudo-Trotter or Qubit-Excitation-based VQE calculations using a loose convergence criteria. Here, the major part of the electron correlation is described using the VQE ansatz circuit and the remaining correlation energy is described by either multireference or similarity transformation-based perturbation theory. Numerical results demonstrate that the new algorithms are able to accurately describe electron correlation of the LiH crystal with only one circuit parameter, in contrast with ~30 parameters required in the adaptive VQE to achieve the same accuracy. Meanwhile, for fixed-depth Ansatze, e.g. unitary coupled cluster, we demonstrate that the VQE-base perturbation theory provides an appealing scheme to improve their accuracy.
{"title":"Perturbative variational quantum algorithms for material simulations","authors":"Jie Liu, Zhenyu Li, Jinlong Yang","doi":"10.1088/2516-1075/ad2277","DOIUrl":"https://doi.org/10.1088/2516-1075/ad2277","url":null,"abstract":"\u0000 Reducing circuit depth is essential for implementing quantum simulations of electronic structure on near-term quantum devices. In this work, we propose a variational quantum eigensolver (VQE) based perturbation theory algorithm to accurately simulate electron correlation of periodic materials with shallow ansatz circuits, which are generated from Adaptive Derivative-Assembled Pseudo-Trotter or Qubit-Excitation-based VQE calculations using a loose convergence criteria. Here, the major part of the electron correlation is described using the VQE ansatz circuit and the remaining correlation energy is described by either multireference or similarity transformation-based perturbation theory. Numerical results demonstrate that the new algorithms are able to accurately describe electron correlation of the LiH crystal with only one circuit parameter, in contrast with ~30 parameters required in the adaptive VQE to achieve the same accuracy. Meanwhile, for fixed-depth Ansatze, e.g. unitary coupled cluster, we demonstrate that the VQE-base perturbation theory provides an appealing scheme to improve their accuracy.","PeriodicalId":502740,"journal":{"name":"Electronic Structure","volume":" 31","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139623321","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}
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