4 References

All publications resulting from use of this program must acknowledge the following.

MOLPRO, a package of ab initio programs designed by H.-J. Werner and P. J. Knowles, version 2002.1, R. D. Amos, A. Bernhardsson, A. Berning, P. Celani, D. L. Cooper, M. J. O. Deegan, A. J. Dobbyn, F. Eckert, C. Hampel, G. Hetzer, P. J. Knowles, T. Korona, R. Lindh, A. W. Lloyd, S. J. McNicholas, F. R. Manby, W. Meyer, M. E. Mura, A. Nicklass, P. Palmieri, R. Pitzer, G. Rauhut, M. Schütz, U. Schumann, H. Stoll, A. J. Stone, R. Tarroni, T. Thorsteinsson, and H.-J. Werner.

Depending on which programs are used, the following references should be cited.

Integral evaluation (SEWARD)
R. Lindh, U. Ryu, and B. Liu, J. Chem. Phys. 95, 5889 (1991).

Integral-direct Implementation
M. Schütz, R. Lindh, and H.-J. Werner, Mol. Phys. 96, 719 (1999).

MCSCF/CASSCF:
H.-J. Werner and P. J. Knowles, J. Chem. Phys. 82, 5053 (1985);
P. J. Knowles and H.-J. Werner, Chem. Phys. Lett. 115, 259 (1985).

See also:

H.-J. Werner and W. Meyer, J. Chem. Phys. 73, 2342 (1980);
H.-J. Werner and W. Meyer, J. Chem. Phys. 74, 5794 (1981);
H.-J. Werner, Adv. Chem. Phys. LXIX, 1 (1987).

Internally contracted MRCI:
H.-J. Werner and P.J. Knowles, J. Chem. Phys. 89, 5803 (1988);
P.J. Knowles and H.-J. Werner, Chem. Phys. Lett. 145, 514 (1988).

See also:

H.-J. Werner and E.A. Reinsch, J. Chem. Phys. 76, 3144 (1982);
H.-J. Werner, Adv. Chem. Phys. LXIX, 1 (1987).

Excited states with internally contracted MRCI:
P. J. Knowles and H.-J. Werner, Theor. Chim. Acta 84, 95 (1992).

Internally contracted MR-ACPF, QDVPT, etc:
H.-J. Werner and P. J. Knowles, Theor. Chim Acta 78, 175 (1990).

The original reference to uncontracted MR-ACPF, QDVPT, MR-ACQQ are:
R. J. Gdanitz and R. Ahlrichs, Chem. Phys. Lett. 143, 413 (1988);
R. J. Cave and E. R. Davidson, J. Chem. Phys. 89, 6798 (1988);
P. G. Szalay and R. J. Bartlett, Chem. Phys. Lett. 214, 481 (1993).

Multireference perturbation theory (CASPT2/CASPT3):
H.-J. Werner, Mol. Phys. 89, 645 (1996);
P. Celani and H.-J. Werner, J. Chem. Phys. 112, 5546 (2000).

Analytical energy gradients and geometry optimization
Gradient integral evaluation (ALASKA): R. Lindh, Theor. Chim. Acta 85, 423 (1993);
MCSCF gradients: T. Busch, A. Degli Esposti, and H.-J. Werner, J. Chem. Phys. 94, 6708 (1991);
MP2 and LMP2 gradients: A. El Azhary, G. Rauhut, P. Pulay, and H.-J. Werner, J. Chem. Phys. 108, 5185 (1998);
QCISD and LQCISD gradients: G. Rauhut and H.-J. Werner, Phys. Chem. Chem. Phys. 3, 4853 (2001); Geometry optimization: F. Eckert, P. Pulay and H.-J. Werner, J. Comp. Chemistry 18, 1473 (1997);
Reaction path following: F. Eckert and H.-J. Werner, Theor. Chem. Acc. 100, 21, 1998.

Harmonic frequencies
G. Rauhut, A. El Azhary, F. Eckert, U. Schumann, and H.-J. Werner, Spectrochimica Acta 55, 651 (1999).

Møller-Plesset Perturbation theory (MP2, MP3, MP4):
Closed-shell Møller-Plesset Perturbation theory up to fourth order [MP4(SDTQ)] is part of the coupled cluster code, see CCSD.

Open-shell Møller-Plesset Perturbation theory (RMP2):
R. D. Amos, J. S. Andrews, N. C. Handy, and P. J. Knowles, Chem. Phys. Lett. 185, 256 (1991).

Coupled-Cluster treatments (QCI, CCSD, BCCD):
C. Hampel, K. Peterson, and H.-J. Werner, Chem. Phys. Lett. 190, 1 (1992) and references therein. The program to compute the perturbative triples corrections has been developed by M. J. O. Deegan and P. J. Knowles, Chem. Phys. Lett. 227, 321 (1994).

Open-shell coupled-cluster (RCCSD, UCCSD):
P. J. Knowles, C. Hampel and H.-J. Werner, J. Chem. Phys. 99, 5219 (1993); Erratum: J. Chem. Phys. 112, 3106 (2000).

Local MP2 (LMP2):
G. Hetzer, P. Pulay, and H.-J. Werner, Chem. Phys. Lett. 290, 143 (1998);
M. Schütz, G. Hetzer, and H.-J. Werner, J. Chem. Phys. 111, 5691 (1999);
G. Hetzer, M. Schütz, H. Stoll, and H.-J. Werner, J. Chem. Phys. 113, 9443 (2000).

Local MP4(SDTQ), CCSD(T), QCISD(T)):
C. Hampel and H.-J. Werner, J. Chem. Phys. 104 6286 (1996);
M. Schütz and H.-J. Werner, J. Chem. Phys. 114, 661 (2001);
M. Schütz and H.-J. Werner, Chem. Phys. Lett. 318, 370 (2000);
M. Schütz, J. Chem. Phys. 113, 9986 (2000).

Full CI (FCI):
P. J. Knowles and N. C. Handy, Chem. Phys. Letters 111, 315 (1984);
P. J. Knowles and N. C. Handy, Comp. Phys. Commun. 54, 75 (1989).

Distributed Multipole Analysis (DMA):
A. J. Stone, Chem. Phys. Letters 83, 233 (1981).

Valence bond:
D. L. Cooper, T. Thorsteinsson, and J. Gerratt, Int. J. Quant. Chem. 65, 439 (1997);
D. L. Cooper, T. Thorsteinsson, and J. Gerratt, Adv. Quant. Chem. 32, 51-67 (1998).
See also ''An overview of the CASVB approach to modern valence bond calculations'', T. Thorsteinsson and D. L. Cooper, in Quantum Systems in Chemistry and Physics. Volume 1: Basic problems and models systems, eds. A. Hernández-Laguna, J. Maruani, R. McWeeny, and S. Wilson (Kluwer, Dordrecht, 2000); pp 303-26.

Spin-orbit coupling:
A. Berning, M. Schweizer, H.-J. Werner, P. J. Knowles, and P. Palmieri, Mol. Phys., 98, 1823 (2000).