Pub Date : 2024-09-02DOI: 10.1088/2516-1075/ad72c2
Yiyuan Wang, Sari J Laihonen, Mikael Unge, Arash A Mostofi
Work function is a fundamental property of metals and is related to many surface-related phenomena of metals. Theoretically, it can be calculated with a metal slab supercell in density functional theory (DFT) calculations. In this paper, we discuss how the commensurability of atomic structure with the underlying fast Fourier transform (FFT) grid affects the accuracy of work function obtained from plane-wave pseudopotential DFT calculations. We show that the macroscopic average potential, which is an important property in work function calculations under the ‘bulk reference’ method, is more numerically stable when it is calculated with commensurate FFT grids than with incommensurate FFT grids. Due to the stability of the macroscopic average potential, work function calculated with commensurate FFT grids shows better convergence with respect to basis set size, vacuum length and slab thickness of a slab supercell. After we control the FFT grid commensurability issue in our work function calculations, we obtain well-converged work functions for Al, Pd, Au and Pt of (100), (110) and (111) surface orientations. For all the metals considered, the ordering of our calculated work functions of the three surface orientations agrees with experiment. Our findings reveal the importance of the FFT grid commensurability issue, which is usually neglected in practice, in obtaining accurate metal work functions, and are also meaningful to other DFT calculations which can be affected by the FFT grid commensurability issue.
{"title":"Improving the precision of work-function calculations within plane-wave density functional theory","authors":"Yiyuan Wang, Sari J Laihonen, Mikael Unge, Arash A Mostofi","doi":"10.1088/2516-1075/ad72c2","DOIUrl":"https://doi.org/10.1088/2516-1075/ad72c2","url":null,"abstract":"Work function is a fundamental property of metals and is related to many surface-related phenomena of metals. Theoretically, it can be calculated with a metal slab supercell in density functional theory (DFT) calculations. In this paper, we discuss how the commensurability of atomic structure with the underlying fast Fourier transform (FFT) grid affects the accuracy of work function obtained from plane-wave pseudopotential DFT calculations. We show that the macroscopic average potential, which is an important property in work function calculations under the ‘bulk reference’ method, is more numerically stable when it is calculated with commensurate FFT grids than with incommensurate FFT grids. Due to the stability of the macroscopic average potential, work function calculated with commensurate FFT grids shows better convergence with respect to basis set size, vacuum length and slab thickness of a slab supercell. After we control the FFT grid commensurability issue in our work function calculations, we obtain well-converged work functions for Al, Pd, Au and Pt of (100), (110) and (111) surface orientations. For all the metals considered, the ordering of our calculated work functions of the three surface orientations agrees with experiment. Our findings reveal the importance of the FFT grid commensurability issue, which is usually neglected in practice, in obtaining accurate metal work functions, and are also meaningful to other DFT calculations which can be affected by the FFT grid commensurability issue.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"15 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206577","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 : 2024-08-21DOI: 10.1088/2516-1075/ad6c96
Mohammed Miniya, Luis M Gaggero-Sager, Miguel E Mora-Ramos, Rolando Pérez-Álvarez, Outmane Oubram
A particular design for multibarrier structure in graphene, yielding a self-similar transport response, is proposed. The potential profile is based on rectangular wells and barriers, generated according independent nth order scaling laws for their heights and widths. The barriers are constructed by means of two distinct approaches (electrostatic or substrate). Dirac equation and transfer matrix approach are used to calculate transmission properties which, in turn, allow to evaluate the conductance via Landauer–Büttiker formalism. It is found that self-similarity with determined scaling rules between nth and (n+1)th generations of transport properties appears when the order of generating laws is equal or greater than n = 7. Our proposal would be the first in which the self-similarity property is transferred from geometry to the spectrum, and consequently, to the transport properties of a quantum heterostructure. Possible ways of practical realization for the proposed structures are commented.
本文提出了一种石墨烯多势垒结构的特殊设计，可产生自相似的传输响应。该势垒剖面基于矩形井和势垒，根据其高度和宽度的独立 n 次阶缩放定律生成。屏障通过两种不同的方法（静电或基底）构建。利用狄拉克方程和传递矩阵方法计算透射特性，进而通过兰道尔-比提克形式主义评估电导。研究发现，当生成定律的阶数等于或大于 n = 7 时，第 n 代和第 (n+1)th 代传输特性之间会出现自相似性，并具有确定的缩放规则。我们的建议将是第一个把自相似性从几何转移到频谱，进而转移到量子异质结构的传输特性的建议。我们还对拟议结构的可能实际实现方式进行了评论。
{"title":"Self-similarity of quantum transport in graphene using electrostatic gate and substrate","authors":"Mohammed Miniya, Luis M Gaggero-Sager, Miguel E Mora-Ramos, Rolando Pérez-Álvarez, Outmane Oubram","doi":"10.1088/2516-1075/ad6c96","DOIUrl":"https://doi.org/10.1088/2516-1075/ad6c96","url":null,"abstract":"A particular design for multibarrier structure in graphene, yielding a self-similar transport response, is proposed. The potential profile is based on rectangular wells and barriers, generated according independent <italic toggle=\"yes\">n</italic>th order scaling laws for their heights and widths. The barriers are constructed by means of two distinct approaches (electrostatic or substrate). Dirac equation and transfer matrix approach are used to calculate transmission properties which, in turn, allow to evaluate the conductance via Landauer–Büttiker formalism. It is found that self-similarity with determined scaling rules between <italic toggle=\"yes\">n</italic>th and <inline-formula>\u0000<tex-math><?CDATA $(n+1)$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mo stretchy=\"false\">(</mml:mo><mml:mi>n</mml:mi><mml:mo>+</mml:mo><mml:mn>1</mml:mn><mml:mo stretchy=\"false\">)</mml:mo></mml:mrow></mml:math><inline-graphic xlink:href=\"estad6c96ieqn1.gif\"></inline-graphic></inline-formula>th generations of transport properties appears when the order of generating laws is equal or greater than <italic toggle=\"yes\">n</italic> = 7. Our proposal would be the first in which the self-similarity property is transferred from geometry to the spectrum, and consequently, to the transport properties of a quantum heterostructure. Possible ways of practical realization for the proposed structures are commented.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"15 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206578","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 : 2024-07-25DOI: 10.1088/2516-1075/ad610f
Lórien MacEnulty, Matteo Giantomassi, Bernard Amadon, Gian-Marco Rignanese and David D O’Regan
Members of the density functional theory (DFT)+U family of functionals are increasingly prevalent methods of addressing errors intrinsic to (semi-) local exchange-correlation functionals at minimum computational cost, but require their parameters U and J to be calculated in situ for a given system of interest, simulation scheme, and runtime parameters. The self-consistent field (SCF) linear response approach offers ab initio acquisition of the U and has recently been extended to compute the J analogously, which measures localized errors related to exchange-like effects. We introduce a renovated post-processor, the lrUJ utility, together with this detailed best-practices guide, to enable users of the popular, open-source Abinit first-principles simulation suite to engage easily with in situ Hubbard parameters and streamline their incorporation into material simulations of interest. Features of this utility, which may also interest users and developers of other DFT codes, include n-degree polynomial regression, error analysis, Python plotting facilities, didactic documentation, and avenues for further developments. In this technical introduction and guide, we place particular emphasis on the intricacies and potential pitfalls introduced by the projector augmented wave method, SCF mixing schemes, and non-linear response, several of which are translatable to DFT+U(+J) implementations in other packages.
密度泛函理论（DFT）+U 系列函数的成员是以最低计算成本解决（半）局部交换相关函数固有误差的日益普遍的方法，但需要针对给定的相关系统、模拟方案和运行时参数就地计算其参数 U 和 J。自洽场（SCF）线性响应方法提供了 U 的原初获取，最近又扩展到类似地计算 J，以测量与类交换效应相关的局部误差。我们介绍了一种新的后处理器 lrUJ 工具，以及这份详细的最佳实践指南，使流行的开源 Abinit 第一性原理模拟套件的用户能够轻松使用原位哈伯德参数，并简化将其纳入相关材料模拟的过程。其他 DFT 代码的用户和开发人员可能也会对该工具的功能感兴趣，其中包括 n 度多项式回归、误差分析、Python 绘图工具、教学文档以及进一步开发的途径。在本技术介绍和指南中，我们特别强调了投影仪增强波方法、SCF 混合方案和非线性响应所带来的复杂性和潜在隐患，其中有几项可转化为其他软件包中的 DFT+U(+J) 实现。
{"title":"Facilities and practices for linear response Hubbard parameters U and J in Abinit","authors":"Lórien MacEnulty, Matteo Giantomassi, Bernard Amadon, Gian-Marco Rignanese and David D O’Regan","doi":"10.1088/2516-1075/ad610f","DOIUrl":"https://doi.org/10.1088/2516-1075/ad610f","url":null,"abstract":"Members of the density functional theory (DFT)+U family of functionals are increasingly prevalent methods of addressing errors intrinsic to (semi-) local exchange-correlation functionals at minimum computational cost, but require their parameters U and J to be calculated in situ for a given system of interest, simulation scheme, and runtime parameters. The self-consistent field (SCF) linear response approach offers ab initio acquisition of the U and has recently been extended to compute the J analogously, which measures localized errors related to exchange-like effects. We introduce a renovated post-processor, the lrUJ utility, together with this detailed best-practices guide, to enable users of the popular, open-source Abinit first-principles simulation suite to engage easily with in situ Hubbard parameters and streamline their incorporation into material simulations of interest. Features of this utility, which may also interest users and developers of other DFT codes, include n-degree polynomial regression, error analysis, Python plotting facilities, didactic documentation, and avenues for further developments. In this technical introduction and guide, we place particular emphasis on the intricacies and potential pitfalls introduced by the projector augmented wave method, SCF mixing schemes, and non-linear response, several of which are translatable to DFT+U(+J) implementations in other packages.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"2 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141770698","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 : 2024-07-18DOI: 10.1088/2516-1075/ad610e
Remi J Leano, Aurora Pribram-Jones and David A Strubbe
Ensemble density functional theory (EDFT) is a generalization of ground-state DFT, which is based on an exact formal theory of finite collections of a system’s ground and excited states. EDFT in various forms has been shown to improve the accuracy of calculated energy level differences in isolated model systems, atoms, and molecules, but it is not yet clear how EDFT could be used to calculate band gaps for periodic systems. We extend the application of EDFT toward periodic systems by estimating the thermodynamic limit with increasingly large finite one-dimensional ‘particle in a box’ systems, which approach the uniform electron gas (UEG). Using ensemble-generalized Hartree and local spin density approximation exchange-correlation functionals, we find that corrections go to zero in the infinite limit, as expected for a metallic system. However, there is a correction to the effective mass, with results comparable to other calculations on 1D, 2D, and 3D UEGs, which indicates promise for non-trivial results from EDFT on periodic systems.
{"title":"Approaching periodic systems in ensemble density functional theory via finite one-dimensional models","authors":"Remi J Leano, Aurora Pribram-Jones and David A Strubbe","doi":"10.1088/2516-1075/ad610e","DOIUrl":"https://doi.org/10.1088/2516-1075/ad610e","url":null,"abstract":"Ensemble density functional theory (EDFT) is a generalization of ground-state DFT, which is based on an exact formal theory of finite collections of a system’s ground and excited states. EDFT in various forms has been shown to improve the accuracy of calculated energy level differences in isolated model systems, atoms, and molecules, but it is not yet clear how EDFT could be used to calculate band gaps for periodic systems. We extend the application of EDFT toward periodic systems by estimating the thermodynamic limit with increasingly large finite one-dimensional ‘particle in a box’ systems, which approach the uniform electron gas (UEG). Using ensemble-generalized Hartree and local spin density approximation exchange-correlation functionals, we find that corrections go to zero in the infinite limit, as expected for a metallic system. However, there is a correction to the effective mass, with results comparable to other calculations on 1D, 2D, and 3D UEGs, which indicates promise for non-trivial results from EDFT on periodic systems.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"16 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141739859","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 : 2024-07-10DOI: 10.1088/2516-1075/ad5e29
Fabian Schrodi, Alex Aperis and Peter M Oppeneer
We study two aspects of the superconductivity in a cuprate model system, its doping dependence and the influence of competing pairing mediators. We first include electron–phonon interactions beyond Migdal’s approximation and solve self-consistently, as a function of doping and for an isotropic electron–phonon coupling, the full-bandwidth, anisotropic vertex-corrected Eliashberg equations under a non-interacting state approximation for the vertex correction. Our results show that such pairing interaction supports the experimentally observed -wave symmetry of the superconducting gap, but only in a narrow doping interval of the hole-doped system. Depending on the coupling strength, we obtain realistic values for the gap magnitude and superconducting critical temperature close to optimal doping, rendering the electron–phonon mechanism an important candidate for mediating superconductivity in this model system. Second, for a doping near optimal hole doping, we study multichannel superconductivity, by including both vertex-corrected electron–phonon interaction and spin and charge fluctuations as pairing mechanisms. We find that both mechanisms cooperate to support an unconventional d-wave symmetry of the order parameter, yet the electron–phonon interaction is mainly responsible for the Cooper pairing and high critical temperature . Spin fluctuations are found to have a suppressing effect on the gap magnitude and critical temperature due to their repulsive interaction at small coupling wave vectors.
我们研究了铜氧化物模型系统超导性的两个方面：其掺杂依赖性和竞争配对介质的影响。我们首先在米格达尔近似之外加入了电子-声子相互作用，并在顶点校正的非相互作用态近似下，自洽地求解了全带宽、各向异性顶点校正的埃利亚斯伯格方程（作为掺杂的函数）和各向同性电子-声子耦合。我们的结果表明，这种配对相互作用支持实验观察到的超导间隙的波对称性，但仅限于掺杂空穴系统的狭窄掺杂区间。根据耦合强度的不同，我们得到了接近最佳掺杂的间隙大小和超导临界温度的实际值，从而使电子-声子机制成为介导该模型系统超导性的重要候选机制。其次，对于接近最佳空穴掺杂的掺杂，我们研究了多通道超导性，将顶点校正电子-声子相互作用以及自旋和电荷波动作为配对机制。我们发现，这两种机制相互配合，支持阶次参数的非传统 d 波对称性，然而电子-声子相互作用是库珀配对和高临界温度的主要原因。由于自旋波动在小耦合波矢量下的排斥作用，它对间隙大小和临界温度有抑制作用。
{"title":"Doping dependence and multichannel mediators of superconductivity: calculations for a cuprate model","authors":"Fabian Schrodi, Alex Aperis and Peter M Oppeneer","doi":"10.1088/2516-1075/ad5e29","DOIUrl":"https://doi.org/10.1088/2516-1075/ad5e29","url":null,"abstract":"We study two aspects of the superconductivity in a cuprate model system, its doping dependence and the influence of competing pairing mediators. We first include electron–phonon interactions beyond Migdal’s approximation and solve self-consistently, as a function of doping and for an isotropic electron–phonon coupling, the full-bandwidth, anisotropic vertex-corrected Eliashberg equations under a non-interacting state approximation for the vertex correction. Our results show that such pairing interaction supports the experimentally observed -wave symmetry of the superconducting gap, but only in a narrow doping interval of the hole-doped system. Depending on the coupling strength, we obtain realistic values for the gap magnitude and superconducting critical temperature close to optimal doping, rendering the electron–phonon mechanism an important candidate for mediating superconductivity in this model system. Second, for a doping near optimal hole doping, we study multichannel superconductivity, by including both vertex-corrected electron–phonon interaction and spin and charge fluctuations as pairing mechanisms. We find that both mechanisms cooperate to support an unconventional d-wave symmetry of the order parameter, yet the electron–phonon interaction is mainly responsible for the Cooper pairing and high critical temperature . Spin fluctuations are found to have a suppressing effect on the gap magnitude and critical temperature due to their repulsive interaction at small coupling wave vectors.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"1 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141586137","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 : 2024-07-08DOI: 10.1088/2516-1075/ad5cb5
Yingfeng Zhang
The atomic and molecular electronic structure program (Amesp) is a general-purpose electronic structure program designed for the study of molecular electronic structures. It incorporates a series of modern electronic structure methods, including Hartree–Fock, density functional theory, Multiconfigurational self-consistent field, Møller–Plesset, configuration-interaction, coupled-cluster, semiempirical methods, and molecular force fields. Amesp strives to offer an efficient and user-friendly tool specifically designed for computing for molecules ranging from small to complex biomolecules. In this paper, we highlight the features of Amesp and offer an overview.
{"title":"Amesp: Atomic and molecular electronic structure program","authors":"Yingfeng Zhang","doi":"10.1088/2516-1075/ad5cb5","DOIUrl":"https://doi.org/10.1088/2516-1075/ad5cb5","url":null,"abstract":"The atomic and molecular electronic structure program (Amesp) is a general-purpose electronic structure program designed for the study of molecular electronic structures. It incorporates a series of modern electronic structure methods, including Hartree–Fock, density functional theory, Multiconfigurational self-consistent field, Møller–Plesset, configuration-interaction, coupled-cluster, semiempirical methods, and molecular force fields. Amesp strives to offer an efficient and user-friendly tool specifically designed for computing for molecules ranging from small to complex biomolecules. In this paper, we highlight the features of Amesp and offer an overview.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"11 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141566711","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 : 2024-07-04DOI: 10.1088/2516-1075/ad5b40
Ariel M Cabrera, Michele Guerrini, Henry P Pinto and Caterina Cocchi
Methylammonium lead iodide (MAPbI3) has been a major focus of photovoltaic research for the last decade. The unique interplay between the structural and electronic properties of this material contributes to its exciting optical properties especially under the action of an ultrafast laser pulse. First-principles methods like real-time time-dependent density functional theory (RT-TDDFT) enable performing corresponding simulations without the aid of empirical parameters: the gained knowledge can be applied to future studies of other complex materials. In this work, we investigate the ultrafast charge-carrier dynamics and the nonlinear optical response of MAPbI3 excited by a resonant pulse above the gap. First, we examine the electronic and optical properties in the static regime. Next, we impinge the system with a femtosecond field of varying intensity and follow the evolution of the photoexcited carrier density. A pronounced intensity-dependent response is observed, manifested by high-harmonic generation and nonlinear trends in the number of excited electrons and excitation energy. Our results provide relevant indications about the behavior of MAPbI3 under strong and coherent radiation and confirm that RT-TDDFT is a viable tool to simulate the photo-induced dynamics of complex materials from first principles.
{"title":"Ultrafast charge carrier dynamics of methylammonium lead iodide from first principles","authors":"Ariel M Cabrera, Michele Guerrini, Henry P Pinto and Caterina Cocchi","doi":"10.1088/2516-1075/ad5b40","DOIUrl":"https://doi.org/10.1088/2516-1075/ad5b40","url":null,"abstract":"Methylammonium lead iodide (MAPbI3) has been a major focus of photovoltaic research for the last decade. The unique interplay between the structural and electronic properties of this material contributes to its exciting optical properties especially under the action of an ultrafast laser pulse. First-principles methods like real-time time-dependent density functional theory (RT-TDDFT) enable performing corresponding simulations without the aid of empirical parameters: the gained knowledge can be applied to future studies of other complex materials. In this work, we investigate the ultrafast charge-carrier dynamics and the nonlinear optical response of MAPbI3 excited by a resonant pulse above the gap. First, we examine the electronic and optical properties in the static regime. Next, we impinge the system with a femtosecond field of varying intensity and follow the evolution of the photoexcited carrier density. A pronounced intensity-dependent response is observed, manifested by high-harmonic generation and nonlinear trends in the number of excited electrons and excitation energy. Our results provide relevant indications about the behavior of MAPbI3 under strong and coherent radiation and confirm that RT-TDDFT is a viable tool to simulate the photo-induced dynamics of complex materials from first principles.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"48 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141551320","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 : 2024-07-02DOI: 10.1088/2516-1075/ad5b33
E Maskar, A Fakhim Lamrani, R Zosiamliana and D P Rai
In this study, we explore the structural, electronic, thermodynamic, and thermoelectric properties of RuO2 using density functional theory. The derived equilibrium structural parameters agree with other theoretical and experimental results. The widely used modified Becke–Johnson (mBJ-GGA) potential is adopted for accurate electronic band gap estimation. To incorporate the effect of the extended orbital of the Ru atom, spin-orbit coupling has been used in combination with the mBJ potential. The investigation of electronic properties revealed an indirect semi-conducting nature with a band gap along the W-L symmetry. The calculated band gaps are 1.685 and 1.658 eV from mBJ and mBJ + SOC, respectively. The dynamical stability is tested and verified by calculating the phonon dispersion curve. We have employed the quasiharmonic approximation-based Gibbs2 package to determine the pressure and temperature-dependent thermodynamical parameters, such as cell volume, Debye temperature, heat capacity, entropy, and thermal expansion coefficient. This study uses the BoltzTraP simulation algorithm to determine the thermoelectric parameters such as the Seebeck coefficient, electrical conductivity, and thermal conductivity.
{"title":"A DFT insight of the electronic, thermodynamic, and thermoelectric properties of RuO2","authors":"E Maskar, A Fakhim Lamrani, R Zosiamliana and D P Rai","doi":"10.1088/2516-1075/ad5b33","DOIUrl":"https://doi.org/10.1088/2516-1075/ad5b33","url":null,"abstract":"In this study, we explore the structural, electronic, thermodynamic, and thermoelectric properties of RuO2 using density functional theory. The derived equilibrium structural parameters agree with other theoretical and experimental results. The widely used modified Becke–Johnson (mBJ-GGA) potential is adopted for accurate electronic band gap estimation. To incorporate the effect of the extended orbital of the Ru atom, spin-orbit coupling has been used in combination with the mBJ potential. The investigation of electronic properties revealed an indirect semi-conducting nature with a band gap along the W-L symmetry. The calculated band gaps are 1.685 and 1.658 eV from mBJ and mBJ + SOC, respectively. The dynamical stability is tested and verified by calculating the phonon dispersion curve. We have employed the quasiharmonic approximation-based Gibbs2 package to determine the pressure and temperature-dependent thermodynamical parameters, such as cell volume, Debye temperature, heat capacity, entropy, and thermal expansion coefficient. This study uses the BoltzTraP simulation algorithm to determine the thermoelectric parameters such as the Seebeck coefficient, electrical conductivity, and thermal conductivity.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"65 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141522500","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 : 2024-07-01DOI: 10.1088/2516-1075/ad5acb
Tappei Kawakami, Kosuke Nakayama, Katsuaki Sugawara and Takafumi Sato
Topotactic chemical reaction (TCR) is a chemical process that transforms one crystalline phase to another while maintaining one or more of the original structural frameworks, typically induced by the local insertion, removal, or replacement of atoms in a crystal. The utilization of TCR in atomic-layer materials and surfaces of bulk crystals leads to exotic quantum phases, as highlighted by the control of topological phases, the emergence of two-dimensional (2D) superconductivity, and the realization of 2D ferromagnetism. Advanced surface-sensitive spectroscopies such as angle-resolved photoemission spectroscopy and scanning tunneling microscopy are leading techniques to visualize the electronic structure of such exotic states and provide us a guide to further functionalize material properties. In this review article, we summarize the recent progress in this field, with particular emphasis on intriguing results obtained by combining spectroscopies and TCR in thin films.
{"title":"In-situ topotactic chemical reaction for spectroscopies","authors":"Tappei Kawakami, Kosuke Nakayama, Katsuaki Sugawara and Takafumi Sato","doi":"10.1088/2516-1075/ad5acb","DOIUrl":"https://doi.org/10.1088/2516-1075/ad5acb","url":null,"abstract":"Topotactic chemical reaction (TCR) is a chemical process that transforms one crystalline phase to another while maintaining one or more of the original structural frameworks, typically induced by the local insertion, removal, or replacement of atoms in a crystal. The utilization of TCR in atomic-layer materials and surfaces of bulk crystals leads to exotic quantum phases, as highlighted by the control of topological phases, the emergence of two-dimensional (2D) superconductivity, and the realization of 2D ferromagnetism. Advanced surface-sensitive spectroscopies such as angle-resolved photoemission spectroscopy and scanning tunneling microscopy are leading techniques to visualize the electronic structure of such exotic states and provide us a guide to further functionalize material properties. In this review article, we summarize the recent progress in this field, with particular emphasis on intriguing results obtained by combining spectroscopies and TCR in thin films.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"143 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141503539","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 : 2024-06-26DOI: 10.1088/2516-1075/ad5945
E Black and J M Morbec
Heterostructures composed of pentacene (PEN) molecules and transition metal dichalchogenides (TMDs) are promising materials for small, flexible and lightweight photovoltaic devices and various other optoelectronic applications. The effects of changing concentration and orientation of adsorbed PEN molecules on two-dimensional monolayer substrates of TMDs, namely MoS2, MoSe2, WS2 and WSe2, were investigated using first-principles calculations based on density functional theory. We examined the structural and electronic properties of the corresponding PEN/TMD heterostructures and compared these between differing PEN concentrations and the orientations of PEN with respect to the underlying substrate crystal structure. We analyze the band alignment of the heterostructures and demonstrate a concentration-dependent staggered-to-straddling (typeII-I) band gap transition in PEN/MoSe2.
{"title":"Effect of molecular rotation and concentration on the adsorption of pentacene molecules on two-dimensional monolayer transition metal dichalcogenides","authors":"E Black and J M Morbec","doi":"10.1088/2516-1075/ad5945","DOIUrl":"https://doi.org/10.1088/2516-1075/ad5945","url":null,"abstract":"Heterostructures composed of pentacene (PEN) molecules and transition metal dichalchogenides (TMDs) are promising materials for small, flexible and lightweight photovoltaic devices and various other optoelectronic applications. The effects of changing concentration and orientation of adsorbed PEN molecules on two-dimensional monolayer substrates of TMDs, namely MoS2, MoSe2, WS2 and WSe2, were investigated using first-principles calculations based on density functional theory. We examined the structural and electronic properties of the corresponding PEN/TMD heterostructures and compared these between differing PEN concentrations and the orientations of PEN with respect to the underlying substrate crystal structure. We analyze the band alignment of the heterostructures and demonstrate a concentration-dependent staggered-to-straddling (typeII-I) band gap transition in PEN/MoSe2.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"44 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141503540","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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