Hi, My question is about SIESTA and how the MeshCutoff is used. The charge density is on a grid and Fourier contributions of the *density* up to E_cutoff are represented. This is equal to four times the E_cutoff used in the PW codes to represent the *basis* functions (i.e. planewaves).
Is the grid on which the two-center integrals, e.g. S(R), T(R), etc., are calculated explicitly related to the MeshCutoff? Or does the MeshCutoff only explicitly control the grid for n(r)? On p. 7 of the SIESTA method paper it states "... we need rather fine radial grids to obtain accurate kinetic matrix elements, and we typically use grid cutoffs of more than 2000 Ry for this purpose." -- Nichols A. Romero, Ph.D. 1613 Denise Dr. Apt. D Forest Hill, MD 21050 443-567-8328 (C) 410-306-0709 (O)
