Electronic Configuration

The next few keys can be used to specify the electronic configuration. If you don't specify any such keys, certain defaults will apply. In principle, the program will (by default) attempt to find the lowest-energy spin-restricted (one-determinant) state. If SCF convergence is problematic the program may wind up at an excited state, by which (in this context) we mean a one-determinant state with a higher energy than some other one-determinant state with the same net spin polarization. In worse cases the program may fail to converge to any state at all. It is good practice to always verify which configuration you actually have computed.

When you specify a particular configuration and/or net charge and/or net spin-polarization of the system, the program will try to compute accordingly, even if the data have no physical or chemical meaning. The program has no knowledge about the existence of materials and will simply try to carry out what you tell it to do.