Pub Date : 2023-10-06DOI: 10.1088/2516-1075/acf974
Antje Vollmer, Raphael Schlesinger, Johannes Frisch
Abstract Synchrotron radiation-based methods, in particular photoemission spectroscopy, are very powerful tools for studying the electronic, chemical, and structural properties of materials and combinations of materials. Numerous experimental studies have been performed in the last decades using synchrotron radiation in physics, chemistry, material science, biology, medicine, and more. However, the advantage of high photon flux from synchrotron storage rings, which is beneficial or even crucial for many experiments, may impose new problems when sensitive samples are investigated, such as organic systems. They are prone to chemical changes when exposed to high photon fluxes. Here, we demonstrate how to identify beam-induced sample degradation and provide the best practice rules for reliable investigations and control experiments.
{"title":"Sample Degradation and Beam-induced Damage in (Synchrotron-based) Electronic Structure Experiments","authors":"Antje Vollmer, Raphael Schlesinger, Johannes Frisch","doi":"10.1088/2516-1075/acf974","DOIUrl":"https://doi.org/10.1088/2516-1075/acf974","url":null,"abstract":"Abstract Synchrotron radiation-based methods, in particular photoemission spectroscopy, are very powerful tools for studying the electronic, chemical, and structural properties of materials and combinations of materials. Numerous experimental studies have been performed in the last decades using synchrotron radiation in physics, chemistry, material science, biology, medicine, and more. However, the advantage of high photon flux from synchrotron storage rings, which is beneficial or even crucial for many experiments, may impose new problems when sensitive samples are investigated, such as organic systems. They are prone to chemical changes when exposed to high photon fluxes. Here, we demonstrate how to identify beam-induced sample degradation and provide the best practice rules for reliable investigations and control experiments.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135302893","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 : 2023-09-29DOI: 10.1088/2516-1075/acfbcf
Martin Mosquera
Abstract The propagation of general electronic quantum states provides information of the interaction of molecular systems with external driving fields. These can also offer understandings regarding non-adiabatic quantum phenomena. Well established methods focus mainly on propagating a quantum system that is initially described exclusively by the ground state wavefunction. In this work, we expand a previously developed size-extensive formalism within coupled cluster theory, called second response theory, so it propagates quantum systems that are initially described by a general linear combination of different states, which can include the ground state, and show how with a special set of time-dependent cluster operators such propagations are performed. Our theory shows strong consistency with numerically exact results for the determination of quantum mechanical observables, probabilities, and coherences. We discuss unperturbed non-stationary states within second response theory and their ability to predict matrix elements that agree with those found in linear and quadratic response theories. This work also discusses an approximate regularized methodology to treat systems with potential instabilities in their ground-state cluster amplitudes, and compares such approximations with respect to reference results from standard unitary theory.
{"title":"Second response theory: A theoretical formalism for the propagation of quantum superpositions","authors":"Martin Mosquera","doi":"10.1088/2516-1075/acfbcf","DOIUrl":"https://doi.org/10.1088/2516-1075/acfbcf","url":null,"abstract":"Abstract The propagation of general electronic quantum states provides information of the interaction of molecular systems with external driving fields. These can also offer understandings regarding non-adiabatic quantum phenomena. Well established methods focus mainly on propagating a quantum system that is initially described exclusively by the ground state wavefunction. In this work, we expand a previously developed size-extensive formalism within coupled cluster theory, called second response theory, so it propagates quantum systems that are initially described by a general linear combination of different states, which can include the ground state, and show how with a special set of time-dependent cluster operators such propagations are performed. Our theory shows strong consistency with numerically exact results for the determination of quantum mechanical observables, probabilities, and coherences. We discuss unperturbed non-stationary states within second response theory and their ability to predict matrix elements that agree with those found in linear and quadratic response theories. This work also discusses an approximate regularized methodology to treat systems with potential instabilities in their ground-state cluster amplitudes, and compares such approximations with respect to reference results from standard unitary theory.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135131737","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 : 2023-09-15DOI: 10.1088/2516-1075/acfa4e
Yuriy Dedkov, Yefei Guo, Elena Voloshina
Abstract The recent progress in the studies of 2D materials placed in front many experimental and theoretical works on the interesting class of materials, the so-called transition metal phosphorus trichalcogenides with structural formula MPX 3 (M: transition metal, X: chalcogen). Here, the diversity in the M/X combination opens the possibility to tune the electronic and magnetic properties of these materials in a very wide range, resulting in many interesting physical phenomena followed by the promoting their use in different application areas. This review gives a timely overview of the recent progress in the fundamental studies of electronic structure and magnetic properties of MPX 3 materials (M: Mn, Fe, Co, Ni, X: S, Se) focusing on the results obtained by density functional theory (DFT), Raman spectroscopy and electron spectroscopy methods. We pay close attention to the large amount of theoretical and experimental data giving critical analysis of the previously obtained results. It is shown how the systematic fundamental studies of the electronic and magnetic properties of MPX 3 can help to understand the functionality of these interesting 2D materials in different applications, ranging from optoelectronics to catalysis.
{"title":"Progress in the studies of electronic and magnetic properties of layered MPX<sub>3</sub> materials (M: transition metal, X: chalcogen)","authors":"Yuriy Dedkov, Yefei Guo, Elena Voloshina","doi":"10.1088/2516-1075/acfa4e","DOIUrl":"https://doi.org/10.1088/2516-1075/acfa4e","url":null,"abstract":"Abstract The recent progress in the studies of 2D materials placed in front many experimental and theoretical works on the interesting class of materials, the so-called transition metal phosphorus trichalcogenides with structural formula MPX 3 (M: transition metal, X: chalcogen). Here, the diversity in the M/X combination opens the possibility to tune the electronic and magnetic properties of these materials in a very wide range, resulting in many interesting physical phenomena followed by the promoting their use in different application areas. This review gives a timely overview of the recent progress in the fundamental studies of electronic structure and magnetic properties of MPX 3 materials (M: Mn, Fe, Co, Ni, X: S, Se) focusing on the results obtained by density functional theory (DFT), Raman spectroscopy and electron spectroscopy methods. We pay close attention to the large amount of theoretical and experimental data giving critical analysis of the previously obtained results. It is shown how the systematic fundamental studies of the electronic and magnetic properties of MPX 3 can help to understand the functionality of these interesting 2D materials in different applications, ranging from optoelectronics to catalysis.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135353548","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}
Abstract Despite rapid progress in the development of quantum algorithms in quantum computing as well as numerical simulation methods in classical computing for atomic and molecular applications, no systematic and comprehensive electronic structure study of atomic systems that covers almost all of the elements in the periodic table using a single quantum algorithm has been reported. In this work, we address this gap by implementing the recently-proposed quantum algorithm, the Bayesian phase difference estimation (BPDE) approach, to determine fine structure splittings of a wide range of boron-like atomic systems. Since accurate estimate of fine structure splittings strongly depend on the relativistic as well as quantum many-body effects, our study can test the potential of the BPDE approach to produce results close to the experimental values. Our numerical simulations reveal that the BPDE algorithm, in the Dirac–Coulomb–Breit framework, can predict fine structure splittings of ground states of the considered systems quite precisely. We performed our simulations of relativistic and electron correlation effects on Graphics Processing Unit by utilizing NVIDIA’s cuQuantum, and observe a ×42.7 speedup as compared to the Central Processing Unit-only simulations in an 18-qubit active space.
{"title":"Bayesian phase difference estimation algorithm for direct calculation of fine structure splitting: accelerated simulation of relativistic and quantum many-body effects","authors":"Kenji Sugisaki, Srinivasa Prasannaa, Satoshi Ohshima, Takahiro Katagiri, Yuji Mochizuki, Bijaya Kumar Sahoo, Bhanu Pratap Das","doi":"10.1088/2516-1075/acf909","DOIUrl":"https://doi.org/10.1088/2516-1075/acf909","url":null,"abstract":"Abstract Despite rapid progress in the development of quantum algorithms in quantum computing as well as numerical simulation methods in classical computing for atomic and molecular applications, no systematic and comprehensive electronic structure study of atomic systems that covers almost all of the elements in the periodic table using a single quantum algorithm has been reported. In this work, we address this gap by implementing the recently-proposed quantum algorithm, the Bayesian phase difference estimation (BPDE) approach, to determine fine structure splittings of a wide range of boron-like atomic systems. Since accurate estimate of fine structure splittings strongly depend on the relativistic as well as quantum many-body effects, our study can test the potential of the BPDE approach to produce results close to the experimental values. Our numerical simulations reveal that the BPDE algorithm, in the Dirac–Coulomb–Breit framework, can predict fine structure splittings of ground states of the considered systems quite precisely. We performed our simulations of relativistic and electron correlation effects on Graphics Processing Unit by utilizing NVIDIA’s cuQuantum, and observe a ×42.7 speedup as compared to the Central Processing Unit-only simulations in an 18-qubit active space.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135889253","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 : 2023-09-01DOI: 10.1088/2516-1075/acf9d3
Diana Propst, Jani Kotakoski, Elina Harriet Åhlgren
Abstract Dispersed impurities in diamond present a flourishing platform for research in quantum informatics, spintronics and single phonon emitters. Based on the vast pool of experimental and theoretical work describing impurity atoms in diamond, we review the configurations by the chemical element discussing the relevant atomic configurations and most important properties. Dopant structures expand from single to co-doping configurations, also combined with carbon vacancies. Despite of their importance, not much is known about the exact atomic configurations associated with the dopant structures beyond computational models, partially due to difficulties in their microscopic observation. To assess the visibility of these structures, we carry out image simulations to show that the heavier dopants may be easily discernible in scanning transmission electron microscopy annular dark field images, with a window of visibility of up to over ± 10 nm in defocus. We further present the first atomic resolution images of an impurity atom configuration (substitutional Er atom) in the diamond lattice, confirmed by a comparison to the simulated images. Overall, our results demonstrate that there is a vast research field waiting for the microscopy community in resolving the exact atomic structure of various impurity atom configurations in diamond.
{"title":"Impurity atom configurations in diamond and their visibility via scanning transmission electron microscopy imaging","authors":"Diana Propst, Jani Kotakoski, Elina Harriet Åhlgren","doi":"10.1088/2516-1075/acf9d3","DOIUrl":"https://doi.org/10.1088/2516-1075/acf9d3","url":null,"abstract":"Abstract Dispersed impurities in diamond present a flourishing platform for research in quantum informatics, spintronics and single phonon emitters. Based on the vast pool of experimental and theoretical work describing impurity atoms in diamond, we review the configurations by the chemical element discussing the relevant atomic configurations and most important properties. Dopant structures expand from single to co-doping configurations, also combined with carbon vacancies. Despite of their importance, not much is known about the exact atomic configurations associated with the dopant structures beyond computational models, partially due to difficulties in their microscopic observation. To assess the visibility of these structures, we carry out image simulations to show that the heavier dopants may be easily discernible in scanning transmission electron microscopy annular dark field images, with a window of visibility of up to over <?CDATA ${pm}$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:mrow> <mml:mo>±</mml:mo> </mml:mrow> </mml:math> 10 nm in defocus. We further present the first atomic resolution images of an impurity atom configuration (substitutional Er atom) in the diamond lattice, confirmed by a comparison to the simulated images. Overall, our results demonstrate that there is a vast research field waiting for the microscopy community in resolving the exact atomic structure of various impurity atom configurations in diamond.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135299637","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 : 2023-08-22DOI: 10.1088/2516-1075/acf2d4
A. M. Valencia, D. Bischof, Sebastian Anhäuser, Marc Zeplichal, A. Terfort, G. Witte, C. Cocchi
The development of advanced experimental and theoretical methods for the characterization of excitations in materials enables revisiting established concepts that are sometimes misleadingly transferred from one field to another without the necessary disclaimers. This is precisely the situation that occurs for excitons in organic materials: different states of matter and peculiarities related to their structural arrangements and their environment may substantially alter the nature of the photo-induced excited states compared to inorganic semiconductors for which the concept of an exciton was originally developed. Adopting the examples of tetracene and perfluorotetracene, in this review, we analyze the nature of the excitations in the isolated compounds in solution, in the crystalline materials, and in melt. Using single crystals or films with large crystalline domains enables polarization-resolved optical absorption measurements, and thus the determination of the energy and polarization of different excitons. These experiments are complemented by state-of-the-art first-principles calculations based on density-functional theory and many-body perturbation theory. The employed methodologies offer unprecedented insight into the optical response of the systems, allowing us to clarify the single-particle character of the excitations in isolated molecules and the collective nature of the electron–hole pairs in the aggregated phases. Our results reveal that the turning point between these two scenarios is the quantum-mechanical interactions between the molecules: when their wave-function distributions and the Coulomb interactions among them are explicitly described in the adopted theoretical scheme, the excitonic character of the optical transitions can be captured. Semi-classical models accounting only for electrostatic couplings between the photo-activated molecules and their environment are unable to reproduce these effects. The outcomes of this work offer a deeper understanding of excitations in organic semiconductors from both theoretical and experimental perspectives.
{"title":"Excitons in organic materials: revisiting old concepts with new insights","authors":"A. M. Valencia, D. Bischof, Sebastian Anhäuser, Marc Zeplichal, A. Terfort, G. Witte, C. Cocchi","doi":"10.1088/2516-1075/acf2d4","DOIUrl":"https://doi.org/10.1088/2516-1075/acf2d4","url":null,"abstract":"The development of advanced experimental and theoretical methods for the characterization of excitations in materials enables revisiting established concepts that are sometimes misleadingly transferred from one field to another without the necessary disclaimers. This is precisely the situation that occurs for excitons in organic materials: different states of matter and peculiarities related to their structural arrangements and their environment may substantially alter the nature of the photo-induced excited states compared to inorganic semiconductors for which the concept of an exciton was originally developed. Adopting the examples of tetracene and perfluorotetracene, in this review, we analyze the nature of the excitations in the isolated compounds in solution, in the crystalline materials, and in melt. Using single crystals or films with large crystalline domains enables polarization-resolved optical absorption measurements, and thus the determination of the energy and polarization of different excitons. These experiments are complemented by state-of-the-art first-principles calculations based on density-functional theory and many-body perturbation theory. The employed methodologies offer unprecedented insight into the optical response of the systems, allowing us to clarify the single-particle character of the excitations in isolated molecules and the collective nature of the electron–hole pairs in the aggregated phases. Our results reveal that the turning point between these two scenarios is the quantum-mechanical interactions between the molecules: when their wave-function distributions and the Coulomb interactions among them are explicitly described in the adopted theoretical scheme, the excitonic character of the optical transitions can be captured. Semi-classical models accounting only for electrostatic couplings between the photo-activated molecules and their environment are unable to reproduce these effects. The outcomes of this work offer a deeper understanding of excitations in organic semiconductors from both theoretical and experimental perspectives.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41862430","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 : 2023-07-18DOI: 10.1088/2516-1075/ace86d
Mårten Skogh, Oskar Leinonen, P. Lolur, M. Rahm
One impediment to the useful application of variational quantum algorithms in quantum chemistry is slow convergence with large numbers of classical optimization parameters. In this work, we evaluate a quantum computational warm-start approach for potential energy surface calculations. Our approach, which is inspired by conventional computational methods, is evaluated using simulations of the variational quantum eigensolver. Significant speedup is demonstrated relative to calculations that rely on a Hartree–Fock initial state, both for ideal and sampled simulations. The general approach of transferring parameters between similar problems is promising for accelerating current and near-term quantum chemistry calculations on quantum hardware, and is likely applicable beyond the tested algorithm and use case.
{"title":"Accelerating variational quantum eigensolver convergence using parameter transfer","authors":"Mårten Skogh, Oskar Leinonen, P. Lolur, M. Rahm","doi":"10.1088/2516-1075/ace86d","DOIUrl":"https://doi.org/10.1088/2516-1075/ace86d","url":null,"abstract":"One impediment to the useful application of variational quantum algorithms in quantum chemistry is slow convergence with large numbers of classical optimization parameters. In this work, we evaluate a quantum computational warm-start approach for potential energy surface calculations. Our approach, which is inspired by conventional computational methods, is evaluated using simulations of the variational quantum eigensolver. Significant speedup is demonstrated relative to calculations that rely on a Hartree–Fock initial state, both for ideal and sampled simulations. The general approach of transferring parameters between similar problems is promising for accelerating current and near-term quantum chemistry calculations on quantum hardware, and is likely applicable beyond the tested algorithm and use case.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46754229","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 : 2023-07-18DOI: 10.1088/2516-1075/ace86c
Thorsten Deilmann, M. Rohlfing, K. Thygesen
Two-dimensional (2D) materials have revealed many fascinating physical and chemical properties. Due to the quantum confinement and enhanced many-body effects especially the optical properties are altered compared to their bulk counterparts. The optics of 2D materials can easily be modified by various means, e.g. the substrate, doping, strain, stacking, electric or magnetic fields. In this review we focus on the theoretical description of the excited states and optical properties of 2D semiconductors paying particular attention to the current challenges and future opportunities. While the presented methodology is completely general and applicable to any 2D material, we discuss results for the transition metal dichalcogenides, their heterostructures, and some novel materials from the computational 2D materials database.
{"title":"Optical excitations in 2D semiconductors","authors":"Thorsten Deilmann, M. Rohlfing, K. Thygesen","doi":"10.1088/2516-1075/ace86c","DOIUrl":"https://doi.org/10.1088/2516-1075/ace86c","url":null,"abstract":"Two-dimensional (2D) materials have revealed many fascinating physical and chemical properties. Due to the quantum confinement and enhanced many-body effects especially the optical properties are altered compared to their bulk counterparts. The optics of 2D materials can easily be modified by various means, e.g. the substrate, doping, strain, stacking, electric or magnetic fields. In this review we focus on the theoretical description of the excited states and optical properties of 2D semiconductors paying particular attention to the current challenges and future opportunities. While the presented methodology is completely general and applicable to any 2D material, we discuss results for the transition metal dichalcogenides, their heterostructures, and some novel materials from the computational 2D materials database.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43247044","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 : 2023-07-05DOI: 10.1088/2516-1075/acde2a
A. Liu, D. Almeida, S. Cundiff, L. Padilha
At low excitation density, the dynamics of excitons in semiconductor nanocrystals are largely dictated by their interactions with the underlying atomic lattice. This exciton-phonon coupling (EPC) is responsible, for example, for absorption and luminescence linewidths at elevated temperatures, relaxation processes following optical excitation, and even degradation of quantum coherent applications. Characterizing and understanding EPC is therefore central to guiding rational design of colloidal nanocrystal materials and their device applications. In this review, we compare different spectroscopic methods of measuring exciton-phonon interactions and the complementary information that they provide. We emphasize the development of a new technique, termed multidimensional coherent spectroscopy, that circumvents many of the limitations of traditional methods.
{"title":"Measuring exciton-phonon coupling in semiconductor nanocrystals","authors":"A. Liu, D. Almeida, S. Cundiff, L. Padilha","doi":"10.1088/2516-1075/acde2a","DOIUrl":"https://doi.org/10.1088/2516-1075/acde2a","url":null,"abstract":"At low excitation density, the dynamics of excitons in semiconductor nanocrystals are largely dictated by their interactions with the underlying atomic lattice. This exciton-phonon coupling (EPC) is responsible, for example, for absorption and luminescence linewidths at elevated temperatures, relaxation processes following optical excitation, and even degradation of quantum coherent applications. Characterizing and understanding EPC is therefore central to guiding rational design of colloidal nanocrystal materials and their device applications. In this review, we compare different spectroscopic methods of measuring exciton-phonon interactions and the complementary information that they provide. We emphasize the development of a new technique, termed multidimensional coherent spectroscopy, that circumvents many of the limitations of traditional methods.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41508714","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 : 2023-07-04DOI: 10.1088/2516-1075/ace0aa
Nanchen Dongfang, Yasmine S Al-Hamdani, M. Iannuzzi
The presence of defects, such as copper and oxygen vacancies, in cuprous oxide films determines their characteristic carrier conductivity and consequently their application as semiconducting systems. There are still open questions on the induced electronic re-distribution, including the formation of polarons. Indeed, to accurately reproduce the structural and electronic properties at the cuprous oxide surface, very large slab models and theoretical approaches that go beyond the standard generalized gradient corrected density functional theory are needed. In this work we investigate oxygen vacancies formed in proximity of a reconstructed Cu2O(111) surface, where the outermost unsaturated copper atoms are removed, thus forming non-stoichiometric surface layers with copper vacancies. We address simultaneously surface and bulk properties by modelling a thick and symmetric slab, to find that hybrid exchange-correlation functionals are needed to describe the oxygen vacancy in this system. Our simulations show that the formation of oxygen vacancies is favoured in the sub-surface layer. Moreover, the oxygen vacancy leads to a splitting and left-shift of the shallow hole states in the gap, which are associated with the deficiency of copper at the surface. These findings suggest that surface electronic structure and reactivity are sensitive to the presence of oxygen vacancies, also when the latter are formed deeper within the film.
{"title":"Understanding the role of oxygen-vacancy defects in Cu2O(111) from first-principle calculations","authors":"Nanchen Dongfang, Yasmine S Al-Hamdani, M. Iannuzzi","doi":"10.1088/2516-1075/ace0aa","DOIUrl":"https://doi.org/10.1088/2516-1075/ace0aa","url":null,"abstract":"The presence of defects, such as copper and oxygen vacancies, in cuprous oxide films determines their characteristic carrier conductivity and consequently their application as semiconducting systems. There are still open questions on the induced electronic re-distribution, including the formation of polarons. Indeed, to accurately reproduce the structural and electronic properties at the cuprous oxide surface, very large slab models and theoretical approaches that go beyond the standard generalized gradient corrected density functional theory are needed. In this work we investigate oxygen vacancies formed in proximity of a reconstructed Cu2O(111) surface, where the outermost unsaturated copper atoms are removed, thus forming non-stoichiometric surface layers with copper vacancies. We address simultaneously surface and bulk properties by modelling a thick and symmetric slab, to find that hybrid exchange-correlation functionals are needed to describe the oxygen vacancy in this system. Our simulations show that the formation of oxygen vacancies is favoured in the sub-surface layer. Moreover, the oxygen vacancy leads to a splitting and left-shift of the shallow hole states in the gap, which are associated with the deficiency of copper at the surface. These findings suggest that surface electronic structure and reactivity are sensitive to the presence of oxygen vacancies, also when the latter are formed deeper within the film.","PeriodicalId":42419,"journal":{"name":"Electronic Structure","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49230057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：