Dear Wien2k users,
I have posted this question last week. Unfortunately, I could not get any suggestions. I ask this again. Which functional LDA or GGA is good for total energy calculations for compounds like NaCl, CsCl. I would like to estimate the enthalpies of some mixed salts like (Na,Cs)Cl. If we see the enthalpy equation for NaCl, we have Enthalpy_NaCl= ENE (NaCl)-1/2*ENE (Na)-1/4*ENE(Cl2) How do we estimate the third term on the right? Which functional? I did the following calculation I placed a chlorine atom in P4/mmm cell at (0,0,0.0606) with a sufficiently large lattice parameters and did the SCF with a single gamma point. I got ENE=-1845.995 Ry I then placed a Cl atom in a Fm3m cell at (0,0,0) and did the calculation for a single gamma point. I got ENE=-922.872 The dissociation energy comes to be -330 kJ/mol which actually is -242.602 kJ/mol. So , how do we estimate E(Cl2) for getting accurate enthalpies of NaCl. Any suggestions please Thanks Suddhasattwa -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20110518/d3eeb0d7/attachment.htm>