mp2r12(1)

Psi Release 2.0 1

mp2r12(1) PSI COMMANDS FOR UNIX USERS mp2r12(1)

NAME
mp2r12 − calculates the MP2-R12 energy in standard approximation A for closed-shell systems.

DESCRIPTION
The program mp2r12 determines the linear-R12 second-order Moller-Plesset energy for closed-shell systems. Input integrals must come from the restricted transformation available in the TRANSQT program. Frozen orbitals are not allowed, as the basis sets used in linear-R12 computations employ basis sets with more than enough flexibility to describe core-correlation effects correctly.

REFERENCES
Moller-Plesset original paper: 1.

C. Moller and M. S. Plesset, "Note on an Approximation Treatment for Many-Electron Systems", Phys. Rev., 46, 618(1934).

Linear R12 theory formulation: 2.

W. Kutzelnigg and W. Klopper, "Wave functions with terms linear in the interelectronic coordinates to take care of the correlation cusp. I. General Theory", J. Chem. Phys., 94, 1985(1991).

MP2-R12/A programmable expressions: 3.

W. Klopper, "Limiting values for Moller-Plesset second-order correlation energies of polyatomic systems: A benchmark study on Ne, HF, H2O, N2, and He...He", J. Chem. Phys., 102, 6168(1995).

FILES REQUIRED

input.dat
FILE30
FILE72 (electron repulsion integrals, produced by transqt)
FILE79 (integrals of r12 operator, produced by transqt)
FILE80 (integrals of [r12,T2] operator, produced by transqt)

FILES GENERATED

output.dat

INPUT OPTIONS
mp2r12 has the following options: PRINT_LVL = integer

Determines the verbosity of the printing information. A print value of 0 gives minimal information, while 5 gives debugging information (do NOT use print levels above 3 for more than 20 basis functions). The default is 0. TOLERANCE = integer
This gives the exponent of the cutoff value for the elimination of two-electron integrals from the list of those on disk. The default is 14, giving a cutoff of 1e-14. FROZEN_DOCC = int_array
Number of frozen doubly-occupied orbitals in each symmetry block. Default is a vector of zeroes. FROZEN_UOCC = int_array
Number of frozen unoccupied orbitals in each symmetry block. Default is a vector of zeroes. C_LIMIT = boolean
Instead of using variationally optimized C-coefficients, use limiting values (1/2 for singlet pairs, 1/4 for triplet pairs). Default is false.

Psi Release 2.0 Last change: 06 August, 1999 1