##master-page:HelpTemplate
##master-date:Unknown-Date
#format wiki
#language en
#Please change following line to BDF module name

= resp =
<<TableOfContents(4)>>

{{{
Response properties based on DFT/HF theory. 
}}}

== Keywords ==

IPRT
METHOD
CHCK
GEOM
LINE
QUAD
FNAC
POLA
HYPE
FDIF
AOPER
BOPER
COPER
BFREQ
CFREQ
REDUCED
NORESP
IGNORE
SINGLE
STATES
DOUBLE
PAIRS
STEP
BOHR
NORDER
NPRT
CTHRD
IPROPS
NFILES

== Quick guides by examples ==
The following examples give the minimal inputs for starting response calculations:

=== Example: first-order NAC ===

{{{

$COMPASS
Title
 nh3
Basis
 sto-3g
Geometry
 C                  0.00000000   -1.20809142   -1.14173975
 C                  0.00000000   -1.20797607    0.25342015
 C                  0.00000000    0.00000000    0.95085852
 C                 -0.00000000    1.20797607    0.25342015
 C                 -0.00000000    1.20809142   -1.14173975
 C                  0.00000000    0.00000000   -1.83922155
 H                  0.00000000   -2.16045397   -1.69142002
 H                  0.00000000   -2.16044427    0.80300713
 H                 -0.00000000    2.16044427    0.80300713
 H                 -0.00000000    2.16045397   -1.69142002
 H                  0.00000000    0.00000000   -2.93882555
 F                  0.00000000    0.00000000    2.30085848
End geometry
skeleton
group
c(1)
nosym
$END

$xuanyuan
direct
schwarz
$end

$scf
RHF
charge
0
spin
1
THRESHCONV
1.d-10 1.d-8
OPTSCR
1
iaufbau
0
$end

$tddft
imethod
1
isf
0
iexit
2
itda
1
idiag
1
istore
1
crit_e
1.d-10
crit_vec
1.d-8
lefteig
AOKXC
DirectGrid
$end

$resp
iprt
1
QUAD
FNAC
single
states
1
1 1 2
double
pairs
1
1 1 1 1 1 2
norder
1
method
2
nfiles
1
FDIF
step
0.001
ignore
1
noresp
$end

}}}

To use finite-difference, a script '''fdiff.py''' should be used as
{{{
./fbdiff.py run.sh input.inp > log
}}}
After the calculation is done, an output file '''input.out''' will present in the current directory. The '''log''' file saves the information during the calculations.

Note: If '''FDIF''' is omitted, the analytic calculation will be carried out by simply using the '''run.sh''' script.