Density functional theory beyond the Born-Oppenheimer approximation: Accurate treatment of the ionic zero-point motion
| Autor: | Grigory Kolesov, Efstratios Manousakis, Efthimios Kaxiras |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Mechanical equilibrium
Physical system Born–Oppenheimer approximation FOS: Physical sciences Zero-point energy Context (language use) 02 engineering and technology 01 natural sciences law.invention Pseudopotential symbols.namesake law Quantum mechanics 0103 physical sciences Physics::Atomic and Molecular Clusters SIESTA (computer program) 010306 general physics Condensed Matter - Statistical Mechanics Physics Condensed Matter - Materials Science Statistical Mechanics (cond-mat.stat-mech) Materials Science (cond-mat.mtrl-sci) 021001 nanoscience & nanotechnology symbols Density functional theory 0210 nano-technology |
| Zdroj: | Physical Review B. 98 |
| ISSN: | 2469-9969 2469-9950 |
| Popis: | We introduce a method to carry out zero-temperature calculations within density functional theory (DFT) but without relying on the Born-Oppenheimer (BO) approximation for the ionic motion. Our approach is based on the finite-temperature many-body path-integral formulation of quantum mechanics by taking the zero-temperature limit and treating the imaginary-time propagation of the electronic variables in the context of DFT. This goes beyond the familiar BO approximation and is limited from being an exact treatment of both electrons and ions only by the approximations involved in the DFT component. We test our method in two simple molecules, H$_2$ and benzene. We demonstrate that the method produces a difference from the results of the BO approximation which is significant for many physical systems, especially those containing light atoms such as hydrogen; in these cases, we find that the fluctuations of the distance from its equilibrium position, due to the zero-point-motion, is comparable to the interatomic distances. The method is suitable for use with conventional condensed matter approaches and currently is implemented on top of the periodic pseudopotential code SIESTA. This version contains some corrections and clarifications |
| Databáze: | OpenAIRE |
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