Bibliography:
Original RS2/RS3:
H.-J. Werner, Mol. Phys. 89, 645-661 (1996)
New internally contracted RS2C:
P. Celani and H.-J. Werner, J. Chem. Phys. 112, 5546 (2000)
All publications resulting from use of this program must acknowledge the above.
The commands
RS2
RS2C
RS3
are used to perform second or third-order perturbation calculations. RS3 always includes RS2 as a first step. For closed-shell single-reference cases, this is equivalent to MP2 or MP3 (but a different program is used). RS2C calls a new more efficient second-order program (see below), which should normally be used if third-order is not required (note that RS3C is not available).