A note on the pulay force at finite temperatures
- Los Alamos National Laboratory
Pulay's original expression for the basis-set dependent adjustment term to the Hellmann-Feynman force in electronic structure theory, which occurs for nonorthogonal local basis-set representations, is based on the idempotency condition of a pure ensemble. At finite electronic temperatures with a fractional occupation of the states, the conventional expression of the Pulay force is therefore no longer valid. Here we derive a simple and computationally efficient expression for a generalized Pulay force, which is suitable for large-scale ab initio simulations at finite electronic temperatures using local nonorthogonal basis-set representations. The generalized Pulay force expression is given in terms of the temperature-dependent density matrix. For the construction of the density matrix, we propose a recursive Fermi operator expansion algorithm that automatically converges to the correct chemical potential.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC52-06NA25396
- OSTI ID:
- 957730
- Report Number(s):
- LA-UR-08-04336; LA-UR-08-4336; JCPSA6; TRN: US1005598
- Journal Information:
- Journal of Chemical Physics, Journal Name: Journal of Chemical Physics; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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