cceom(1) · DOKK

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cceom - equation of motion coupled cluster energy program

DESCRIPTION

The program cceom calculates EOM-CCSD energies using a Davidson algorithm to solve for the right-hand eigenvectors of the CC Hamiltonian.

COMMAND LINE ARGUMENTS

After internal coordinates are detected or generated, optking will enter a run-time mode dependent on command line arguments.

--dot_with_Lg    -  check the orthogonality of the excited right-hand eigenvector with


                 -  the ground state left eigenvector, lambda.  cclambda must be run


                 - first for this to work

REFERENCES

1.: The equation of motion coupled-cluster method. A systematic biorthogonal approach to molecular excitation energies, transition probabilities, and excited state properties, J. F. Stanton and R. J. Bartlett, J. Chem. Phys. 98, 7029 (1993).
EOM_REFERENCE = integer: specifies the algorithm used by cceom. useful for debugging. also must currently be set to ROHF, if you want to get triplet excited states from a singlet ground state. The default is whatever "REFERENCE" is.
STATES_PER_IRREP = array of integers: specifies the number of states of each irreducible representation desired. For example, in C2v symmetry, (0 2 0 0) specifies two excited states of A2 symmetry to be solved, regardless of the symmetry of the ground state.
PROP_SYM = integer: specifies the symmetry of the state that should be used to compute properties. defaults to the last irrep for which states are requested.
PROP_ROOT = integer: specifies the number of the root (within its irrep) that should be used to compute properties. defaults to the highest root requested.
EXCITATION_RANGE = excitation_range: used to generate initial guesses. the larger the value, the more initial guesses are made in the Davidson algorithm.
RESIDUAL_TOL = integer: Davidson algorithm will converge until the norm of the residual vector is less than 10^(-integer). default if 4.
EVAL_TOL = integer: Davidson algorithm will converge until the change in the excitation energy is less than 10^(-integer). default if 6.

Sept 2002