problems with noscf

Just Got Here	4:36:50 AM PDT - Wed, Jul 3rd 2013 Hi, I have a problem using the noscf in a dft calculation. I performed an ordinary DFT calculation and used then the output MOs for a new NOSCF run. I expected to get in both calculations exactly the same energy, but I didn't. For the total energy the deviation is very small but for the contributions from the Coulomb or XC part I get large deviations. I converted then from both runs the output movecs files to ASCII and compared the coefficients. They are different. Now, I'm a bit confused about the meaning of the NOSCF option. I expected to have no changes in the coefficients and exactly the same energy as in the previous run. Maybe someone here can help me understand what NOSCF does. Thanks a lot for your help.

Forum Regular	9:20:09 AM PDT - Wed, Jul 3rd 2013 Hi Mo, The NOSCF option suppresses the SCF cycles. So a single Fock-matrix is constructed but the orbitals are not optimized. However, when the program reads the vectors in it does an orthonormalization before entering the SCF driver. This might cause small differences, but it should not introduce any significant changes. Huub

Just Got Here	9:20:10 AM PDT - Thu, Jul 4th 2013 Hi Huub, thanks a lot for your immediate help. Could you give me a hint where I have to modify the code to switch off this orthonormalization? Mo

Forum >> NWChem's corner >> Running NWChem