| 9:27:13 AM PST - Fri, Dec 28th 2018 |
|
| Simply increasing the number of iterations is only a crude way to try to achieve convergence; if your calculation hasn't converged after a couple hundred iterations, it is not likely to converge with the current settings. Achieving convergence in SCF calculations is a bit of an art and very often system dependent. Assuming that you do not have an error in your input (e.g. a bad geometry, unrealistic charge, etc.), some useful approaches could be to converge the calculation with a smaller basis set and then project that solution on to the basis set that is desired (https://github.com/nwchemgit/nwchem/wiki/Hartree-Fock-Theory-for-Molecules#vectors----inpu...) or play with the convergence controls to modify when damping, DIIS, and level-shifting are used (https://github.com/nwchemgit/nwchem/wiki/Density-Functional-Theory-for-Molecules#convergen...). Which specific combinations of modifications will work (if any will work) will depend on the system being studied and the behavior of the SCF cycles.
|