Well I'm not talking about the Born Oppenheimer approximation, which has nothing to to with my question!
Potential energy has a clear meaning in mechanics. If you put kinetic and potential together what you have is total or internal energy. It is terminology? Sure ... but I guess it is somehow misleading. On Fri, Feb 18, 2011 at 2:23 PM, aguado <[email protected]>wrote: > > > On Fri, 18 Feb 2011, N H wrote: > > Hi all, >> >> Are you sure it is correct to say that E_KS is the system's "potential" >> energy? What >> about the kinetic energy use to calculate the Kohn-Sham levels? >> Cheers >> >> NH >> >> > This is again terminology: Yes, the potential energy of your system > includes the kinetic energy of the electrons. When you do molecular dynamics > with a parameterized empirical potential, your potential energy function > also includes the kinetic energy of electrons in an implicit way. > > The kinetic energy of electrons is needed to calculate the potential energy > surface which determines the forces on atoms. This is just Born-Oppenheimer > approximation. Your kinetic energy is purely ionic if you want to study the > dynamics of ions. Everything else goes to the (effective, if you wish) > potential energy. > > Andres Aguado >
