Pub Date : 2023-11-27DOI: 10.1088/2516-1075/ad0d83
Rahul Verma, Bikash Patra, Bahadur Singh
KZnBi was discovered recently as a new three-dimensional Dirac semimetal with a pair of bulk Dirac fermions in contrast to the Z2 trivial insulator reported earlier. In order to address this discrepancy, we have performed electronic structure and topological state analysis of KZnBi using the local, semilocal, and hybrid exchange-correlation (XC) functionals within the density functional theory framework. We find that various XC functionals, including the SCAN meta-GGA and hybrid functional with 25% Hartree–Fock (HF) exchange (HSE06), resolve a topological nonsymmorphic insulator state with the glide-mirror protected hourglass surface Dirac fermions. By carefully tuning the XC strength in modified Becke-Johnson (mBJ) potential, we recover the correct orbital ordering and Dirac semimetal state of KZnBi. We further show that increasing the default HF exchange in hybrid functional (>40%) can also capture the desired Dirac semimetal state with the correct orbital ordering of KZnBi. The calculated energy dispersion and carrier velocities of Dirac states are found to be in excellent agreement with the available experimental results. Our results demonstrate that KZnBi is a unique topological material where large XC effects are crucial to producing the Dirac semimetal state.
{"title":"Topological nonsymmorphic insulator versus Dirac semimetal in KZnBi","authors":"Rahul Verma, Bikash Patra, Bahadur Singh","doi":"10.1088/2516-1075/ad0d83","DOIUrl":"https://doi.org/10.1088/2516-1075/ad0d83","url":null,"abstract":"KZnBi was discovered recently as a new three-dimensional Dirac semimetal with a pair of bulk Dirac fermions in contrast to the <inline-formula>\u0000<tex-math><?CDATA $mathbb{Z}_2$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msub><mml:mrow><mml:mi mathvariant=\"double-struck\">Z</mml:mi></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:math>\u0000<inline-graphic xlink:href=\"estad0d83ieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> trivial insulator reported earlier. In order to address this discrepancy, we have performed electronic structure and topological state analysis of KZnBi using the local, semilocal, and hybrid exchange-correlation (XC) functionals within the density functional theory framework. We find that various XC functionals, including the SCAN meta-GGA and hybrid functional with 25% Hartree–Fock (HF) exchange (HSE06), resolve a topological nonsymmorphic insulator state with the glide-mirror protected hourglass surface Dirac fermions. By carefully tuning the XC strength in modified Becke-Johnson (mBJ) potential, we recover the correct orbital ordering and Dirac semimetal state of KZnBi. We further show that increasing the default HF exchange in hybrid functional (<inline-formula>\u0000<tex-math><?CDATA $gt$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mo>></mml:mo></mml:math>\u0000<inline-graphic xlink:href=\"estad0d83ieqn2.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>40%) can also capture the desired Dirac semimetal state with the correct orbital ordering of KZnBi. The calculated energy dispersion and carrier velocities of Dirac states are found to be in excellent agreement with the available experimental results. Our results demonstrate that KZnBi is a unique topological material where large XC effects are crucial to producing the Dirac semimetal state.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"26 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138691466","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 : 2023-11-24DOI: 10.1088/2516-1075/ad0d82
Arwa Albar, Anjana E Sudheer, D Murali, S Assa Aravindh
The structural stability and electronic properties of two dimensional PtSSe/SrTiO3 Janus heterostructures were investigated using density functional theory calculations, considering both S and Se terminations into account. Ab-initio thermodynamics simulations revealed that the heterostructure formed with Se/Ti interface termination is more stable with an energy difference of 1.53 eV than the S/Ti termination. In contrast to the semiconducting nature of the free standing monolayers, electronic structure analysis revealed metallic behavior for the PtSSe/SrTiO3 heterostructures. Possible charge transfer scenario is envisaged from SrTiO3 to PtSSe, and type III (broken gap) band alignment is obtained for the heterostructure which is desirable for tunneling applications. The favorable energetic stability of these heterostructures indicate the possibility of realizing them in real-time experimental fabrication, and PtSSe/SrTiO3 heterostructures can be promising for energy-efficient future-generation electronics.
利用密度泛函理论计算研究了二维 PtSSe/SrTiO3 Janus 异质结构的结构稳定性和电子特性，同时考虑了 S 和 Se 两种终止方式。Ab-initio 热力学模拟显示，Se/Ti 界面终止形成的异质结构比 S/Ti 终止形成的异质结构更稳定，能量差为 1.53 eV。与独立单层的半导体性质相反，电子结构分析表明 PtSSe/SrTiO3 异质结构具有金属特性。设想了从 SrTiO3 到 PtSSe 之间可能发生的电荷转移情况，并获得了异质结构的 III 型（断隙）带排列，这对于隧道应用来说是非常理想的。这些异质结构具有良好的能量稳定性，表明有可能在实时实验制造中实现它们，PtSSe/SrTiO3 异质结构有望用于高能效的未来一代电子器件。
{"title":"Electronic properties of two dimensional PtSSe/SrTiO3 Janus Van der Waals heterostructures","authors":"Arwa Albar, Anjana E Sudheer, D Murali, S Assa Aravindh","doi":"10.1088/2516-1075/ad0d82","DOIUrl":"https://doi.org/10.1088/2516-1075/ad0d82","url":null,"abstract":"The structural stability and electronic properties of two dimensional PtSSe/SrTiO<sub>3</sub> Janus heterostructures were investigated using density functional theory calculations, considering both S and Se terminations into account. <italic toggle=\"yes\">Ab-initio</italic> thermodynamics simulations revealed that the heterostructure formed with Se/Ti interface termination is more stable with an energy difference of 1.53 eV than the S/Ti termination. In contrast to the semiconducting nature of the free standing monolayers, electronic structure analysis revealed metallic behavior for the PtSSe/SrTiO<sub>3</sub> heterostructures. Possible charge transfer scenario is envisaged from SrTiO<sub>3</sub> to PtSSe, and type III (broken gap) band alignment is obtained for the heterostructure which is desirable for tunneling applications. The favorable energetic stability of these heterostructures indicate the possibility of realizing them in real-time experimental fabrication, and PtSSe/SrTiO<sub>3</sub> heterostructures can be promising for energy-efficient future-generation electronics.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"os-24 1","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138691385","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 : 2023-11-10DOI: 10.1088/2516-1075/ad018f
Carlos Mejuto-Zaera, Alexander F Kemper
Abstract A typical task for classical and quantum computing in chemistry is finding a potential energy surface (PES) along a reaction coordinate, which involves solving the quantum chemistry problem for many points along the reaction path. Developing algorithms to accomplish this task on quantum computers has been an active area of development, yet finding all the relevant eigenstates along the reaction coordinate remains a difficult problem, and determining PESs is thus a costly proposal. In this paper, we demonstrate the use of a eigenvector continuation—a subspace expansion that uses a few eigenstates as a basis—as a tool for rapidly exploring PESs. We apply this to determining the binding PES or torsion PES for several molecules of varying complexity. In all cases, we show that the PES can be captured using relatively few basis states; suggesting that a significant amount of (quantum) computational effort can be saved by making use of already calculated ground states in this manner.
{"title":"Quantum Eigenvector Continuation for Chemistry Applications","authors":"Carlos Mejuto-Zaera, Alexander F Kemper","doi":"10.1088/2516-1075/ad018f","DOIUrl":"https://doi.org/10.1088/2516-1075/ad018f","url":null,"abstract":"Abstract A typical task for classical and quantum computing in chemistry is finding a potential energy surface (PES) along a reaction coordinate, which involves solving the quantum chemistry problem for many points along the reaction path. Developing algorithms to accomplish this task on quantum computers has been an active area of development, yet finding all the relevant eigenstates along the reaction coordinate remains a difficult problem, and determining PESs is thus a costly proposal. In this paper, we demonstrate the use of a eigenvector continuation—a subspace expansion that uses a few eigenstates as a basis—as a tool for rapidly exploring PESs. We apply this to determining the binding PES or torsion PES for several molecules of varying complexity. In all cases, we show that the PES can be captured using relatively few basis states; suggesting that a significant amount of (quantum) computational effort can be saved by making use of already calculated ground states in this manner.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"75 13","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135088350","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 : 2023-11-08DOI: 10.1088/2516-1075/ad0abf
Martik Aghajanian, Arash A Mostofi, Johannes Lischner
Abstract We present theoretical calculations of the optical spectrum of monolayer MoS2 with a charged defect. In particular, we solve the Bethe-Salpeter equation based on an atomistic tight-binding model of the MoS2 electronic structure which allows calculations for large supercells. The defect is modelled as a point charge whose potential is screened by the MoS2 electrons. We find that the defect gives rise to new peaks in the optical spectrum approximately 100-200 meV below the first free exciton peak. These peaks arise from transitions involving in-gap bound states induced by the charged defect. Our findings are in good agreement with experimental measurements.
{"title":"Optical Properties of Charged Defects in Monolayer MoS<sub>2</sub>","authors":"Martik Aghajanian, Arash A Mostofi, Johannes Lischner","doi":"10.1088/2516-1075/ad0abf","DOIUrl":"https://doi.org/10.1088/2516-1075/ad0abf","url":null,"abstract":"Abstract We present theoretical calculations of the optical spectrum of monolayer MoS2 with a charged defect. In particular, we solve the Bethe-Salpeter equation based on an atomistic tight-binding model of the MoS2 electronic structure which allows calculations for large supercells. The defect is modelled as a point charge whose potential is screened by the MoS2 electrons. We find that the defect gives rise to new peaks in the optical spectrum approximately 100-200 meV below the first free exciton peak. These peaks arise from transitions involving in-gap bound states induced by the charged defect. Our findings are in good agreement with experimental measurements.&#xD;","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":" 21","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135341421","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 : 2023-11-07DOI: 10.1088/2516-1075/ad0a3d
Shin-ichi Fujimori, Ikuto Kawasaki, Yukiharu Takeda, Hiroshi Yamagami, Norimasa Sasabe, Yoshiki J Sato, A Nakamura, Yusei Shimizu, Arvind Maurya, Y Homma, D. X. Li, Fuminori Honda, Dai Aoki
Abstract The electronic structure of the f -based superconductor CeIr 3 was studied by photoelectron spectroscopy. The energy distribution of the Ce 4 f state was revealed by the Ce 3 d − 4 f resonant photoelectron spectroscopy. The Ce 4 f state was mostly distributed in the vicinity of the Fermi energy, suggesting the itinerant character of the Ce 4 f state. The contribution of the Ce 4 f state to the density of states (DOS) at the Fermi energy was estimated to be nearly half of that of the Ir 5 d states, implying that the Ce 4 f state has a considerable contribution to the DOS at the Fermi energy. The Ce 3 d core-level and Ce 3 d X-ray absorption spectra were analyzed based on a single-impurity Anderson model. The number of the Ce 4 f state in the ground state was estimated to be 0.8 − 0.9, which is much larger than the values obtained in the previous studies (i.e., 0 − 0.4).
{"title":"Impact of the Ce 4<i>f</i> states in the electronic structure of the intermediate-valence superconductor CeIr<sub>3</sub>","authors":"Shin-ichi Fujimori, Ikuto Kawasaki, Yukiharu Takeda, Hiroshi Yamagami, Norimasa Sasabe, Yoshiki J Sato, A Nakamura, Yusei Shimizu, Arvind Maurya, Y Homma, D. X. Li, Fuminori Honda, Dai Aoki","doi":"10.1088/2516-1075/ad0a3d","DOIUrl":"https://doi.org/10.1088/2516-1075/ad0a3d","url":null,"abstract":"Abstract The electronic structure of the f -based superconductor CeIr 3 was studied by photoelectron spectroscopy. The energy distribution of the Ce 4 f state was revealed by the Ce 3 d − 4 f resonant photoelectron spectroscopy. The Ce 4 f state was mostly distributed in the vicinity of the Fermi energy, suggesting the itinerant character of the Ce 4 f state. The contribution of the Ce 4 f state to the density of states (DOS) at the Fermi energy was estimated to be nearly half of that of the Ir 5 d states, implying that the Ce 4 f state has a considerable contribution to the DOS at the Fermi energy. The Ce 3 d core-level and Ce 3 d X-ray absorption spectra were analyzed based on a single-impurity Anderson model. The number of the Ce 4 f state in the ground state was estimated to be 0.8 − 0.9, which is much larger than the values obtained in the previous studies (i.e., 0 − 0.4).","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"13 12","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135480581","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 : 2023-11-02DOI: 10.1088/2516-1075/ad0951
Gang Bahadur Acharya, Bishnu Prasad Belbase, Madhav Prasad Ghimire
Abstract Recent research focuses on electronic structure of kagome materials due to their fascinating properties such as topological insulators, Dirac semimetals, and topological superconductors. Materials with sizable electronic band gap are found to play vital role in device applications. Here, by means of density functional theory calculations, we study the electronic and optical properties of ternary transition metal sulphide Cs 2 Ni 3 S 4 by using the Full Potential Local Orbital code. Standard generalized gradient approximation (GGA) has been employed to consider the electron exchange and correlation effect, and modified Becke-Johnson (mBJ) potential has been used to obtain the accurate band gap of the material. From our electronic structure calculations Cs 2 Ni 3 S 4 is found to be nonmagnetic semiconductor with an indirect band gap of ∼1.4 eV within GGA+mBJ calculations. The structural analysis demonstrates that Ni atoms form a kagome lattice in a two-dimensional plane, resulting in the presence of a dispersionless flat band located below the Fermi energy. From the optical calculations, analyzing the dielectric function, loss function, and optical conductivity, Cs 2 Ni 3 S 4 is found to be optically active in the visible as well as lower ultraviolet energy ranges. This suggests that Cs 2 Ni 3 S 4 may be a suitable candidate for the optoelectronic devices. Additionally, this work may provides a foundation for the development of optoelectronic device and a framework for experimental work. We additionally investigated the effect of vacancy defects in Cs 2 Ni 3 S 4 to see it’s influence on the electronic and magnetic properties. Interestingly, the Cs-vacancy defect give rise to half-metallic ferromagnetism with an effective magnetic moment of 1 μ Β per unit cell.
{"title":"Electronic structure, optical properties and defect induced half-metallic ferromagnetism in kagome Cs<sub>2</sub>Ni<sub>3</sub>S<sub>4</sub>","authors":"Gang Bahadur Acharya, Bishnu Prasad Belbase, Madhav Prasad Ghimire","doi":"10.1088/2516-1075/ad0951","DOIUrl":"https://doi.org/10.1088/2516-1075/ad0951","url":null,"abstract":"Abstract Recent research focuses on electronic structure of kagome materials due to their fascinating properties such as topological insulators, Dirac semimetals, and topological superconductors. Materials with sizable electronic band gap are found to play vital role in device applications. Here, by means of density functional theory calculations, we study the electronic and optical properties of ternary transition metal sulphide Cs 2 Ni 3 S 4 by using the Full Potential Local Orbital code. Standard generalized gradient approximation (GGA) has been employed to consider the electron exchange and correlation effect, and modified Becke-Johnson (mBJ) potential has been used to obtain the accurate band gap of the material. From our electronic structure calculations Cs 2 Ni 3 S 4 is found to be nonmagnetic semiconductor with an indirect band gap of ∼1.4 eV within GGA+mBJ calculations. The structural analysis demonstrates that Ni atoms form a kagome lattice in a two-dimensional plane, resulting in the presence of a dispersionless flat band located below the Fermi energy. From the optical calculations, analyzing the dielectric function, loss function, and optical conductivity, Cs 2 Ni 3 S 4 is found to be optically active in the visible as well as lower ultraviolet energy ranges. This suggests that Cs 2 Ni 3 S 4 may be a suitable candidate for the optoelectronic devices. Additionally, this work may provides a foundation for the development of optoelectronic device and a framework for experimental work. We additionally investigated the effect of vacancy defects in Cs 2 Ni 3 S 4 to see it’s influence on the electronic and magnetic properties. Interestingly, the Cs-vacancy defect give rise to half-metallic ferromagnetism with an effective magnetic moment of 1 μ Β per unit cell.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"26 7","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135875742","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 : 2023-10-19DOI: 10.1088/2516-1075/acff9e
Van Binh Vu, Jean-Luc Bubendorff, Louis Donald Mouafo, Sylvain Latil, Ahmad Zaarour, Jean-Francois Dayen, Laurent Simon, Yannick J Dappe
Abstract In this work, we study theoretically and experimentally graphene/aluminum oxide interfaces as 0D/2D interfaces for quantum electronics as the nature of the interface is of paramount importance to understand the quantum transport mechanism. Indeed, the electronic transport is driven either by a channel arising from a strong hybridization at the interface, or by tunneling across a van der Waals interface, with very different electric characteristics. By combining electronic spectroscopy and scanning microscopy with density functional theory calculations, we show that the interface is of weak and van der Waals nature. Quantum transport measurements in a single electron transistor confirm this result. Our results provide a first insight into the interfacial properties van der Waals materials based single electron device, and the key role played by the control of the interface states. The weak van der Waals coupling reported is promising for single electron device, where the control of the environmental charges is known to be a key challenge towards applications. Moreover, the unique vertical device architecture, enabled by the dual role of graphene including its vertical electric field transparency, opens the doors for a new class of single electron devices with higher scaling capability and functionalities. This work paves the way to new atomic environment control in single electron device.
{"title":"Graphene/Aluminum oxide interfaces for nanoelectronic devices","authors":"Van Binh Vu, Jean-Luc Bubendorff, Louis Donald Mouafo, Sylvain Latil, Ahmad Zaarour, Jean-Francois Dayen, Laurent Simon, Yannick J Dappe","doi":"10.1088/2516-1075/acff9e","DOIUrl":"https://doi.org/10.1088/2516-1075/acff9e","url":null,"abstract":"Abstract In this work, we study theoretically and experimentally graphene/aluminum oxide interfaces as 0D/2D interfaces for quantum electronics as the nature of the interface is of paramount importance to understand the quantum transport mechanism. Indeed, the electronic transport is driven either by a channel arising from a strong hybridization at the interface, or by tunneling across a van der Waals interface, with very different electric characteristics. By combining electronic spectroscopy and scanning microscopy with density functional theory calculations, we show that the interface is of weak and van der Waals nature. Quantum transport measurements in a single electron transistor confirm this result. Our results provide a first insight into the interfacial properties van der Waals materials based single electron device, and the key role played by the control of the interface states. The weak van der Waals coupling reported is promising for single electron device, where the control of the environmental charges is known to be a key challenge towards applications. Moreover, the unique vertical device architecture, enabled by the dual role of graphene including its vertical electric field transparency, opens the doors for a new class of single electron devices with higher scaling capability and functionalities. This work paves the way to new atomic environment control in single electron device.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135666681","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 : 2023-10-16DOI: 10.1088/2516-1075/acfe68
Austin Mroz, Lukas Turcani, Kim Jelfs
Abstract Molecular structure plays an important role in the selectivity and performance of catalysts. Understanding the impact of structural differences on catalyst performance via quantitative structure-selectivity relationships is key to developing high-performing catalytic systems. There are several methods that have been introduced to quantify steric contributions, including Tolman cone angles, Charton parameters, and A-values. While these have shown promise in predicting selectivity, they access similar, general steric contributions and are largely empirically derived. Alternatively, Sterimol parameters offer a specific multi-directional measure of steric bulk in the form of three vectors in units of distance. Recently, these parameters revealed strong correlations between structure and selectivity in asymmetric catalysis. Yet, despite their demonstrated performance, Sterimol parameters are commonly derived using van der Waals radii, which approximate molecular size using hard-spheres. This method may not accurately describe highly polarized systems. Recently, a new chemical system size metric based on the electric-field of a molecule was developed, which accesses the occupied space of a molecule. Here, we demonstrate that the electric field-derived Sterimol parameters reveal similar structure-selectivity relationships in asymmetric catalysis as conventional Sterimol parameters. Specifically, we present a computational workflow for calculating Sterimol parameters based on the size of a molecule’s electric field, and validate our method using several asymmetric catalysis reactions.
{"title":"Computational workflow for steric assessment using the electric field-derived size","authors":"Austin Mroz, Lukas Turcani, Kim Jelfs","doi":"10.1088/2516-1075/acfe68","DOIUrl":"https://doi.org/10.1088/2516-1075/acfe68","url":null,"abstract":"Abstract Molecular structure plays an important role in the selectivity and performance of catalysts. Understanding the impact of structural differences on catalyst performance via quantitative structure-selectivity relationships is key to developing high-performing catalytic systems. There are several methods that have been introduced to quantify steric contributions, including Tolman cone angles, Charton parameters, and A-values. While these have shown promise in predicting selectivity, they access similar, general steric contributions and are largely empirically derived. Alternatively, Sterimol parameters offer a specific multi-directional measure of steric bulk in the form of three vectors in units of distance. Recently, these parameters revealed strong correlations between structure and selectivity in asymmetric catalysis. Yet, despite their demonstrated performance, Sterimol parameters are commonly derived using van der Waals radii, which approximate molecular size using hard-spheres. This method may not accurately describe highly polarized systems. Recently, a new chemical system size metric based on the electric-field of a molecule was developed, which accesses the occupied space of a molecule. Here, we demonstrate that the electric field-derived Sterimol parameters reveal similar structure-selectivity relationships in asymmetric catalysis as conventional Sterimol parameters. Specifically, we present a computational workflow for calculating Sterimol parameters based on the size of a molecule’s electric field, and validate our method using several asymmetric catalysis reactions.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136078208","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 : 2023-10-09DOI: 10.1088/2516-1075/ad018e
Leonardo Ratini, Chiara Capecci, Leonardo Guidoni
Abstract Exploiting the invariance of the molecular Hamiltonian by unitary transformation of the orbitals it is possible to significantly shorter the depth of the variational circuit in Variational Quantum Eigensolver (VQE) approach by using the Wavefunction-Adapted Hamiltonian Through Orbital Rotation (WAHTOR) algorithm.
In this work, we introduce a non-adiabatic version of the WAHTOR algorithm and compare its efficiency with different implementations (two adiabatic and two non-adiabatic) through estimating Quantum Processing Unit (QPU) resources in prototypical benchmarking systems. Calculating first and second order derivatives of the Hamiltonian at fixed VQE parameters does not introduce a significant QPU overload, leading to results on small molecules that indicate the adiabatic Newton-Raphson method as the more convenient choice. On the contrary, we find out that in the case of Hubbard model systems the trust region non-adiabatic optimization is more efficient.
The preset work therefore indicates clearly the best optimization strategies for empirical variational ansatzes, facilitating the optimization of larger variational wavefunctions for quantum computing.
{"title":"Optimization strategies in WAHTOR algorithm for quantum computing empirical ansatz: a comparative study","authors":"Leonardo Ratini, Chiara Capecci, Leonardo Guidoni","doi":"10.1088/2516-1075/ad018e","DOIUrl":"https://doi.org/10.1088/2516-1075/ad018e","url":null,"abstract":"Abstract Exploiting the invariance of the molecular Hamiltonian by unitary transformation of the orbitals it is possible to significantly shorter the depth of the variational circuit in Variational Quantum Eigensolver (VQE) approach by using the Wavefunction-Adapted Hamiltonian Through Orbital Rotation (WAHTOR) algorithm.&#xD;In this work, we introduce a non-adiabatic version of the WAHTOR algorithm and compare its efficiency with different implementations (two adiabatic and two non-adiabatic) through estimating Quantum Processing Unit (QPU) resources in prototypical benchmarking systems. Calculating first and second order derivatives of the Hamiltonian at fixed VQE parameters does not introduce a significant QPU overload, leading to results on small molecules that indicate the adiabatic Newton-Raphson method as the more convenient choice. On the contrary, we find out that in the case of Hubbard model systems the trust region non-adiabatic optimization is more efficient.&#xD;The preset work therefore indicates clearly the best optimization strategies for empirical variational ansatzes, facilitating the optimization of larger variational wavefunctions for quantum computing.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135044838","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 : 2023-10-06DOI: 10.1088/2516-1075/acfd75
Kushal Ramakrishna, Mani Lokamani, Andrew Baczewski, Jan Vorberger, Attila Cangi
Abstract We present a comprehensive investigation of the electrical and thermal conductivity of iron under high pressures at ambient temperature, employing the real-time formulation of time-dependent density functional theory (RT-TDDFT). Specifically, we examine the influence of a Hubbard correction (+ U ) to account for strong electron correlations. Our calculations based on RT-TDDFT demonstrate that the evaluated electrical conductivity for both high-pressure body-centered cubic (BCC) and hexagonal close-packed (HCP) iron phases agrees well with experimental data. Furthermore, we explore the anisotropy in the thermal conductivity of HCP iron under high pressure, and our findings are consistent with experimental observations. Interestingly, we find that the incorporation of the + U correction significantly impacts the ground state and linear response properties of iron at pressures below 50 GPa, with its influence diminishing as pressure increases. This study offers valuable insights into the influence of electronic correlations on the electronic transport properties of iron under extreme conditions.
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