expandmo

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

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.

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