Self-consistency

The SCF procedure searches for a self-consistent density. The self-consistent error is the square root of the integral of the squared difference between the input and output density of the cycle operator. When the SCF error is below a certain criterion, controlled by subkey Criterion of block key Convergence, convergence is reached. In case of bad convergence the SCF look at the subkeys Mixing, and Degenerate, and the subkey block DIIS .