Dear siesta users: I have now encounter a question: the results differ when using different number of core to parallel.
1 core: siesta: 124 -33928.6003 -33928.6031 -33928.6366 0.0002 -4.1261 siesta: 125 -33928.6004 -33928.6012 -33928.6346 0.0001 -4.1251 siesta: 126 -33928.6003 -33928.6009 -33928.6344 0.0001 -4.1258 siesta: E_KS(eV) = -33928.6012 siesta: E_KS - E_eggbox = -33928.6012 12 core: siesta: 123 -33928.6004 -33928.6064 -33928.6398 0.0003 -4.1246 siesta: 124 -33928.6003 -33928.6026 -33928.6360 0.0001 -4.1257 siesta: 125 -33928.6003 -33928.6018 -33928.6352 0.0001 -4.1256 siesta: 126 -33928.6004 -33928.5996 -33928.6331 0.0001 -4.1253 siesta: E_KS(eV) = -33928.6001 siesta: E_KS - E_eggbox = -33928.6001 The E_KS differs 0.001 eV. I think it is significant. I think the number of core using to paralle only affect the speed. The results should be the same. Or there is something I am missing? And I have another question: when I do the geometry optimization, which energy is used to calculated the force? And when I do molecular dynamics, which energy is used for the force? I think the KS energy of a single point DFT calculation and the KS energy of a molecular dynamics should be the same for the same structure. Am I right? Any suggestions will be regarded. Best Guangping 2012-03-24 Guangping Zhang
