VASP使用经验总结—By Rosen Review.docx

第 第 PAGE #页共7页 VASP使用经验总结一By Rosen Review 目录 TOC \o 1-5 \h \z \o Current Document Geometry Optimizations 1 \o Current Document Choice of Optimization Algorithms 2 \o Current Document Electronic Energy Convergence 3 \o Current Document Spin Polarization 5 \o Current Document Transition States 5 \o Current Document Spin/Charge Densities 5 \o Current Document Pseudopotentials 6 \o Current Document Parallel Performance 6 \o Current Document ASE 6 Rosen Review：我在这里包括一些积累的VASP智慧。这些技巧中有许多 是经验法则，所以要考虑对你感兴趣的特定体系进行研究。 Geometry Optimizations Dont waste your time using super high-accuracy settings on a structure far from the local minimum. Do an initial optimization with looser settings (e.g. gamma-point only for the k-point grid, 400 eV cutoff if relaxing the atomic positions) and then refine it with the desired parameters. When performing geometry optimizations that involve changes in the cell shape and/or volume, always ensure that ENCUT 1.3*ENMAX to prevent Pulay stresses. For structures containing carbon, this often means using a minimum cutoff of 520 eV. The first step in a geometry optimization will generally have the highest number of SCF iterations. It is okay if that first step does not converge electronically within the limits of NELM. In fact, it is better to have the first step reach NELM instead of running for many hundreds of SCF iterations. The general rule-of-thumb is to set EDIFFG to 0.05 eV/A or lower for optimizations. I personally recommend 0.03 eV/A or lower. For large, flexible materials, any value greater than 0.03 eV/A is likely too high. Remember that in VASP, the EDIFFG flag must be a negative value if you want a convergence threshold based on the maximum net force, not the change in total energy. When performing a full optimization of atomic positions and cell shape/volume, it is almost always best to do this in stages. It is often wise to start with a relaxation of the atomic positions (ISIF=2) followed by a full volume relaxati