21.4 Level shifts

Level shifts are often useful to avoid intruder state problems in excitated 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

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

Typical choices for the shift is are $0.1 - 0.3$. The shift affects the results, and 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.

For more special shift settings see option SHIFTE0 below.