Portal de Periódicos da CAPES

Screened-exchange stress tensor in density functional theory

2006; American Physical Society; Volume: 73; Issue: 12 Linguagem: Inglês

10.1103/physrevb.73.125120

1550-235X

Michael C. Gibson, S. Brand, Stewart J. Clark,

Advanced Chemical Physics Studies

We have derived and implemented the theory for directly computing the contribution to the stress tensor ${\ensuremath{\sigma}}_{\ensuremath{\alpha}\ensuremath{\beta}}$ from exchange and correlation effects when using the screened exchange method in Kohn-Sham density functional theory (DFT). The method is also applicable when using related functionals such as Hartree-Fock or exact exchange. This paves the way for full geometric relaxation of a crystal structure when using such functionals, without the need for expensive numerical differentiation. The theory is derived in reciprocal space, appropriate for plane-wave based calculations, and has been implemented within an efficient, and fully parallel, DFT code. As a simple demonstration of the validity of this method we calculate the variation in stress as both hydrostatic and shear strains are applied to silicon when using screened exchange.