2001/04/10 by L. C. Balbas, Jose Luis Martins, Jose M. Soler
Physics and Astronomy · #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.64.165110
published as Phys. Rev. B 64, 165110 (2001) · 7 pages, 3 figures
arxiv created 2001/04/10 · arxiv updated 2009/11/30
We describe a method for calculating the exchange and correlation (XC) contributions to the total energy, effective potential, and stress tensor in the generalized gradient approximation. We avoid using the analytical expressions for the functional derivatives of Exc*rho, which depend on discontinuous second-order derivatives of the electron density rho. Instead, we first approximate Exc by its integral in a real space grid, and then we evaluate its partial derivatives with respect to the density at the grid points. This ensures the exact consistency between the calculated total energy, potential, and stress, and it avoids the need of second-order derivatives. We show a few applications of the method, which requires only the value of the (spin) electron density in a grid (possibly nonuniform) and returns a conventional (local) XC potential.