OpenCAP
Electronic structure of metastable states
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Q-Chem is a widely used quantum chemistry package with a variety of open-shell and excited state electronic structure methods. We officially support an interface with EOM-CC calculations performed by Q-Chem. There is also an experimental TDDFT interface.
OpenCAP can extract the basis set from .fchk files generated by Q-Chem.
Relevant keywords
Keyword | Valid options | Description |
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molecule | molden,rassi_h5,inline,qchem_fchk | Specifies which format to read the molecular geometry. If "inline" is chosen, the "$geometry" section is also required. |
basis_file | path to basis file | Specifies the path to the basis file. When "molecule" is set to "molden","rassi_h5", or "qchem_fchk", this keyword should be set to a path to a file of the specified type. When "molecule" is set to "inline", this keyword should be set to a path to a basis set file formatted in "Psi4" style. |
Densities can be read in from .fchk files, and the zeroth order Hamiltonian can be read from Q-Chem output files for EOM-CC calculations. To export the full densities to .fchk, GUI=2 must be set in the $rem card, and PROJ_CAP=3 must be set in the $complex_ccman card. See the Q-Chem manual for more details.
Separate alpha/beta densities and spin traced one particle densities are both supported, and are automatically detected by OpenCAP.
Relevant keywords
Keyword | Type | Description |
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qchem_fchk | string | Relative or absolute path to .fchk file containing TDMs. |
qchem_output | string | Relative or absolute path to Q-Chem output file. |
h0_file | string | Relative or absolute path to properly formatted zeroth order Hamiltonian file. |
Example input
$system molecule qchem_fchk basis_file qc_input.fchk $end $projected_cap method eom package qchem qchem_fchk qc_input.fchk nstates 10 CAP_TYPE voronoi R_CUT 3.00 Radial_precision 14 Angular_points 110 $end