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2.2 Running Q-Chem

2.2.3 Customizable Archive Files

(December 11, 2025)

Q-Chem supports a customizable archive file which permits the saving of various data from the calculation. The contents of the archive is controlled via data keywords specified in the $schema section of the input file. The format of the schema is in YAML and currently the level of indentation must be exactly 2 spaces.

The following data keywords are valid within the $schema section:

ApproxHessian ContractionCoefficients Coordinates
DensityMatrix Energy FockMatrix
Gradient NAlpha NBeta
Nuclei OrbitalCoefficients OrbitalEnergies
OrthonormalizationMatrix OverlapMatrix PrimitiveExponents
PrimitivesPerShell ShellCoordinates ShellToAtomMap
ShellTypes SpContractionCoefficients TotalCharge

Data can be nested allowing, for example, not just the final MO coefficients to be printed, but those for each cycle of the SCF as well. The following container levels are available and are used to control this level of nesting:

BasisSet GeomOpt GeomOptStep
SCF SCFStep Structure

The archive is written to $QCSCRATCH/savename/qch5_archive.h5 and the contents can be accessed using standard HDF5 tools.

Example 2.2  Sample input showing a custom schema specification for the archive file in the $schema section. In the first job the SCF data have been nested which requests the MO coefficients to be printed on each cycle. In the second job, basis set data similar to those in the formatted checkpoint file have been requested.

$molecule
0 1
C          0.00000       -0.00000       -0.68020
C         -0.00000        0.00000        0.68020
H         -0.00000       -0.89374       -1.19620
H          0.00000        0.89374       -1.19620
H         -0.00000       -0.89374        1.19620
H          0.00000        0.89374        1.19620
$end

$rem
  JOBTYPE  opt
  METHOD   hf
  BASIS    sto-3g
$end

$schema
GeomOpt
  GeomOptStep
    SCF
      Energy
      OrbitalCoefficients
$end

@@@

$molecule
  read
$end

$rem
  METHOD    hf
  BASIS     sto-3g
$end

$schema
SCF
  Energy
  FockMatrix
  DensityMatrix
  OrbitalCoefficients
BasisSet
  ShellTypes
  ShellToAtomMap
  ShellCoordinates
  PrimitivesPerShell
  PrimitiveExponents
  ContractionCoefficients
  SpContractionCoefficients
$end