Positivity preserving density matrix minimization at finite temperatures via square root

We present a Wave Operator Minimization (WOM) method for calculating the Fermi–Dirac density matrix for electronic structure problems at finite temperature while preserving physicality by construction using the wave operator, i.e., the square root of the density matrix. WOM models cooling a state in...

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Bibliographic Details
Published in:The Journal of chemical physics 2024-02, Vol.160 (7)
Main Authors: Leamer, Jacob M., Dawson, William, Bondar, Denys I.
Format: Article
Language:English
Subjects:
Atomic properties
Chemical potential
Density
Electronic structure
Optimization
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Summary:We present a Wave Operator Minimization (WOM) method for calculating the Fermi–Dirac density matrix for electronic structure problems at finite temperature while preserving physicality by construction using the wave operator, i.e., the square root of the density matrix. WOM models cooling a state initially at infinite temperature down to the desired finite temperature. We consider both the grand canonical (constant chemical potential) and canonical (constant number of electrons) ensembles. Additionally, we show that the number of steps required for convergence is independent of the number of atoms in the system. We hope that the discussion and results presented in this article reinvigorate interest in density matrix minimization methods.
ISSN:0021-9606
1089-7690
DOI:10.1063/5.0189864