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52.4 Error correction schemes


The ALTER directive of the SURF program allows to provide error correction schemes for individual single point calculations. For example, in case that the Hartree Fock calculation for a certain grid point did not converge and the ORBITAL directive in the subsequent electron correlation calculation uses the IGNORE_ERROR option, an alternative calculation scheme can be provided, e.g. MCSCF in contrast to RHF. In the case of multi level calculations the ALT2D and ALT3D options can be set according to the START2D and START3D options. Note that the energy variable has to be the same in the original method and the alternative.

Alternative procedure to calculate the 1D single points.
Alternative procedure to calculate the 2D single points.
Alternative procedure to calculate the 3D single points.

Note that DFT calculations often still converge when RHF calculations already fail to do so. 2018-01-18