22.5 Level shifts

Level shifts are often useful to avoid intruder state problems in excited state calculations. MOLPRO allows the use of shifts as described by Roos and Andersson, [Chem. Phys. Lett. 245, 215 (1995)]. The shift can be specified on the RS2 or RS2C card

RS2[,G$n$][,SHIFT=shift]
RS2C[,G$n$][,SHIFT=shift]

Typical choices for the shift is are $0.1 - 0.3$. Only two figures after the decimal point are considered. The shift affects the results, the printed energies as well as the ENERGY variable include the energy correction for the shift as proposed by Roos and Andersson. At convergence, also the uncorrected energies are printed for comparison.