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= expandmo =


<<TableOfContents(4)>>

{{{
     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 ==

== Expert keywords ==

= Depend Files =

|| Filename || Description || Format ||
||  task.chkfil1        ||  Check file of the small basis set calculation.            ||  Binary      ||
||  task.chkfil2        ||  Check file of the large basis set calculation.            ||  Binary      ||
|| INPORB               || MO coefficients file of small basis set calculation.     ||  Fomatted ||
|| task.exporb        || Expanded MO coefficients. Save in BDF_WORKDIR     || Formatted ||

= 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 scratch directory.
%mv $BDF_WORKDIR/ch2.scforb $BDF_TMPDIR/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

$expandmo
$end

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

$xuanyuan
$end

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

}}}