On Tue, May 24, 2011 at 4:03 PM, Amin Torabi <amin.torabi at gmail.com> wrote: > Hi all, > ../examples/example03/README says that "The molecule is put in a cubic box > of side 12 bohr" > My questions are: > > how did you chose it to be 12? I tried different numbers and noticed that > the total energy depends on this value.
Indeed. Energy_of_system=Energy_of_molecule+Interaction_energy_with_neighboring_molecules. Different box sizes yield different Interaction energies. > Is it not a calculation on an isolated molecule? cause for an isolated > molecule, it should not be important what the size of the box is. No, it is not. It is a calculation of bunch of molecules. By changing box size, you change the interaction between those molecules. Eventually, those interactions are almost negligible, you'll get isolated molecules. > -------------------------------------------------- Duy Le PhD Student Department of Physics University of Central Florida. "Men don't need hand to do things"
