Hi-
I am trying to calculate the chemical potential of H in a bunch of metals. When I use a single cell, I get results that compare to experiment. However, when I use a 2x2x2 super-cell, I expect to get a more accurate result since the super-cell should model the physical properties more accurately. However, the super-cell results don't even have the right shape. The results look rather random. Any insights into what could be wrong? Here are more details of what I am doing: To get the chemical potential, I put the a number of H atoms at random into the available O-sites. Because there can be a large number H-atoms configurations, I take an average of sample SCF energies. I build the super-cell using the same techniques as in this forum - and I check the structure and configuration with Xcrysden before calculating its energy. Because the lattice constant changes depending on the number of absorbed H, I relax it at each concentration. My reference configuration is a H2 molecule in a large box (same size as the supercell) Thanks in advance Peter Student, EECS, MIT -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20100910/f0053bc5/attachment.htm
