Ab initio molecular dynamics: Theory and Implementation

¢¢¢¢¤£¤¤¤¢¢¢¢c i (G)F α I,iP I α (G), S I(G)FC i (G) nonlocal+i = 1 . . .N b+V loc (R)FC i (G) kineticV loc forcemoduleFC i (G) localFC i (G)Figure 11. Flow chart for the calculation of the forces on the wavefunctions. Notice that thecalculation of the overlap terms FI,i α is done outside the loop over wavefunctions. Besides thewavefunctions and the local potential, the structure factors and the projectors of the nonlocalpseudopotential are input parameters to this module.c i (G)∆V Ilocal (G) n(G) nI c(G) S I (G)F α I,i , dF α I,i,s¢ ¢∂E PPnonlocal∂R I,s∂E PPlocal∂R I,s∂E H∂R I,s∂E ovrl∂R I,s∂E tot∂R I,sFigure 12. Flow chart for the calculation of the forces on the nuclei.preconditioning schemes have been proposed 616,610,308,344 . The preconditioner implementedin the CPMD code is based on the diagonal of the Kohn–Sham matrixH G,G ′, which is given byK G,G ′ = H G,G δ G,G ′ if |G| ≥ G cK G,G ′ = H Gc,G cδ G,G ′ if |G| ≤ G c, (208)66