Dear pwscf experts, I am doing some calculations about incorporation of arsenate ions into lattice of gypsum. But I am not clear how to calculate the overall reaction energy. For example, I calculated the total energy of gypsum supercell (2*1*2) and arsenate incorporated gypsum supercell. But for AsO43- and SO42- ions, I just calculated the total energy of AsO4 with -3 charge and SO4 group with -2 charge in a cubic box (15 * 15 * 15A). Then the overall reaction energy was calculated from the difference between the total energy of products and reactants as following equation. Ca16S16O96H64 + AsO43- = Ca16AsS15O96H64- + SO42-
Did I do right thing? If not, can any expert show me how to calculate correctly? By the way, one more question is the lower total energy means more stable crystal? Thanks in advance. Best, Shaofeng -------------------------------------- Shaofeng Wang, Ph.D of Geochemistry Environmental Molecular Science Group Institute of Applied Ecology, Chinese Academy of Sciences Shenyang, 110016, China [email protected] www.iae.cas.cn _______________________________________________ Pw_forum mailing list [email protected] http://pwscf.org/mailman/listinfo/pw_forum
