> 1. Is it possible to optimize the geometry (with the lattice parameters and > atom positions simultaneously, not just E-V or fixed c/a ratios, etc.) with > wien2k?
No and yes. WIEN2k does not have a "stress tensor", thus optimization of lattice parameters can only be done by total energy. In volume optimization (x optimize; optimize.job) one can easily replace run_lapw by min_lapw and thus simultaneously optimize vol and internal position. Similar, 2D optimizations (a,c) can be done fairly easily at moderate costs (scripts available), maybe also a 3D case is still feasable. However, for a "triclinic" case a 6D search by E-tot only is hardly possible. > 2. I wish to know the unit or dimension of Gmax (usually taken as 14)? I > thought it is the unit of displacement (bohr radius). Any comments? GMAX is the magnitude of the largest K-vector in the Fourier expansion of rho and V. The k-vectors are given in units of 2pi/a and a is specified in atomic units (bohr). Thus Gmax has bohr^(-1). Gmax^2 is the "energy cutoff" in Ry, and such a definition is often used in PP calculations. -- ----------------------------------------- Peter Blaha Inst. Materials Chemistry, TU Vienna Getreidemarkt 9, A-1060 Vienna, Austria Tel: +43-1-5880115671 Fax: +43-1-5880115698 email: pblaha at theochem.tuwien.ac.at -----------------------------------------
