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Applying quantum chemistry to solids and liquids

Electronic structure studies of crystalline solids are dominated by density functional theory (DFT), which has proved capable of providing many powerful insights. Nevertheless, using conventional local, gradient corrected or hybrid functionals, these have a number of short-comings. Perhaps most seriously there is no clear route for systematic improvement of accuracy. A number of wavefunction-based methods have been developed to model crystalline solids, including quantum Monte Carlo and techniques that extend quantum chemical electronic structure methods to include periodic boundary conditions, with recent focus on periodic MP2 implementations. This talk concentrates on alternative methods which seek to address the electron correlation problem in solids using molecular electronic structure calculations on fragments. We outline the incremental scheme (or method of increments) and a hierarchial method. The chief advantage of such schemes over full periodic implementations is their simplicity, and the straightforward extension to more advanced electronic structure methods. We describe some recent applications including solid LiH, LiF, HF and crystalline neon. Liquids present further challenges for any theoretical method. We describe a many-body expansion technique aimed directly at the simulation of molecular liquids. We employ the many-body expansion to reduce the problem to a set of calculations on dimers, trimers etc., and we treat higher-order effects through a polarizable model which uses ab initio properties. MP2-level radial distribution functions for liquid water are presented

Universitat de Girona. Departament de Química

Universitat de Girona. Institut de Química Computacional

Autor: Allan, Neil
Data: 7 juliol 2010
Resum: Electronic structure studies of crystalline solids are dominated by density functional theory (DFT), which has proved capable of providing many powerful insights. Nevertheless, using conventional local, gradient corrected or hybrid functionals, these have a number of short-comings. Perhaps most seriously there is no clear route for systematic improvement of accuracy. A number of wavefunction-based methods have been developed to model crystalline solids, including quantum Monte Carlo and techniques that extend quantum chemical electronic structure methods to include periodic boundary conditions, with recent focus on periodic MP2 implementations. This talk concentrates on alternative methods which seek to address the electron correlation problem in solids using molecular electronic structure calculations on fragments. We outline the incremental scheme (or method of increments) and a hierarchial method. The chief advantage of such schemes over full periodic implementations is their simplicity, and the straightforward extension to more advanced electronic structure methods. We describe some recent applications including solid LiH, LiF, HF and crystalline neon. Liquids present further challenges for any theoretical method. We describe a many-body expansion technique aimed directly at the simulation of molecular liquids. We employ the many-body expansion to reduce the problem to a set of calculations on dimers, trimers etc., and we treat higher-order effects through a polarizable model which uses ab initio properties. MP2-level radial distribution functions for liquid water are presented
Format: video/H263
audio/mpeg
Cita: Allan, N. (2010). Applying quantum chemistry to solids and liquids. A ’IX Girona Seminar’. Girona: Universitat. [Consulta 6 setembre 2010]. Disponible a: http://hdl.handle.net/10256.1/1722
Accés al document: http://hdl.handle.net/10256.1/1722
Llenguatge: eng
Editor: Universitat de Girona. Departament de Química
Universitat de Girona. Institut de Química Computacional
Col·lecció: IX Girona Seminar
Drets: Aquest document està subjecte a una llicència Creative Commons: Reconeixement - No comercial - Compartir igual (by-nc-sa)
URI Drets: http://creativecommons.org/licenses/by-nc-sa/3.0/es/deed.ca
Matèria: Química quàntica -- Congressos
Quantum chemistry -- Congresses
Títol: Applying quantum chemistry to solids and liquids
Tipus: info:eu-repo/semantics/lecture
Repositori: DUGiMedia

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