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7.11 Coupled-Cluster Excited-State and Open-Shell Methods

7.11.30 Interface with OpenFermion package for quantum computing

(April 13, 2024)

Q-Chem provides a capability to dump all quantities required for interfacing with the OpenFermion package 553 J. R. McClean et. al
Quantum Science and Technology
(2020), 5, pp. 034014.
Link
(and similar softwares) for quantum computation. This feature is controlled by the PRINT_QIS keyword. Setting it to TRUE activates the dump: Fock operator, two-electron integrals, and energies of molecular orbitals are saved in separate files in the home directory. OpenFermion (development version, soon to be checked into official github repository) contains an import module, which understands how to read these files, and several unit tests. Example 7.11.30 illustrates this capability for water molecule.

Note:  Core should not be frozen.

PRINT_QIS

PRINT_QIS
       Requests to dump stuff needed for OpenFermion.
TYPE:
       LOGICAL
DEFAULT:
       FALSE
OPTIONS:
       TRUE Print stuff for QIS in user directory.
RECOMMENDATION:
       Beware of size of the files.

Example 7.131  CCSD/STO-3G calculation of water molecule with print-out for OpenFermion.

$comment
Water molecule in STO-3G basis
$end

$molecule
0 1
  H    0.5355326   -0.0489506    0.7341984
  O    0.0563012    0.0114119   -0.1303093
  H   -0.9024750   -0.0253772    0.1144725
$end

$rem
method = ccsd
basis = sto-3g
print_qis = true
gui = 2
n_frozen_core = 0
$end