expandmo

Module expandmo is used to expand molecular orbital from a small basis set into a large basis set and construct automated  MCSCF active space by Atomic Valence Active Space (AVAS) based on target atomic valence orbitals. This module can be used to generate initial guess orbital of a large basis set calculation from the converged orbital of a small basis set calculation. Also, the expanded orbital can be used in dual-basis calculation approaches. AVAS is proposed by Garnet Kin-Lic Chan (JCTC, 13, 4063-4078, 2017.)

General keywords

Overlap

Overlap is used to expand molecular orbital from a small basis set into a large basis set.

AVAS

Atomic Valence Active Space (AVAS) is used to automated construction MCSCF active space by set atomic valence orbitals.

For example: set five 3d atomic orbitals as target atomic orbitals. example file is test086.inp

AVAS

5

1Co|3D-2

1Co|3D-1

1Co|3D0

1Co|3D1

1Co|3D2

Expert keywords

Scri

set threshold to cut small overlap between MOs and target atomic orbitals. Default : 0.1

For example:

Scri 0.2

Depend Files

Examples

• Here, we would calculate CH2 molecule by a small basis set CC-PVDZ. Then the converged orbital will be expanded to aug-CC-PVDZ and used as the initial orbital for SCF calculation. The input file "ch2.inp" looks like

# First we perform a small basis set calculation by using CC-PVDZ.
$COMPASS
Title
 CH2 Molecule test run, cc-pvdz
Basis
 cc-pvdz
Geometry
 C     0.000000        0.00000        0.31399
 H     0.000000       -1.65723       -0.94197
 H     0.000000        1.65723       -0.94197
End geometry
UNIT
 Bohr
Check
$END

$XUANYUAN
$END

$SCF
RHF
Occupied
3  0  1  0
$END

#Change the name of check file.
%mv $BDF_WORKDIR/ch2.chkfil $BDF_WORKDIR/ch2.chkfil1
#Copy SCF converged orbital to work directory inporb.
%mv $BDF_WORKDIR/ch2.scforb $BDF_WORKDIR/ch2.inporb

# Then we init a large basis set calculation by using aug-CC-PVDZ

$COMPASS
Title
 CH2 Molecule test run, aug-cc-pvdz
Basis
 aug-cc-pvdz
Geometry
 C     0.000000        0.00000        0.31399
 H     0.000000       -1.65723       -0.94197
 H     0.000000        1.65723       -0.94197
End geometry
UNIT
 Bohr
Check
$END

# Change name of check file for large basis set.
%mv $BDF_WORKDIR/ch2.chkfil $BDF_WORKDIR/test001_1.chkfil2

# Now we expand orbital.
$expandmo
$end

# Change name of check file for large basis set.
%mv $BDF_WORKDIR/ch2.chkfil2 $BDF_WORKDIR/ch2.chkfil
# Copy expanded orbital to work directory scforb as initial guess orbital.
%mv $BDF_WORKDIR/ch2.exporb $BDF_WORKDIR/ch2.scforb

$xuanyuan
$end

# Read expanded orbital as initial guess orbital.
$scf
RHF
Occupied
 3 0 1 0
Guess
 Read
$end