Showing posts with label frequency scaling parameter. Show all posts
Showing posts with label frequency scaling parameter. Show all posts

18 September 2012

240. Harmonic frequency scaling in NWChem

...is difficult to find information about, but apparently it IS possible:
http://www.emsl.pnl.gov/docs/nwchem/nwchem-support/2012/08/0021._NWCHEM_FW:_BOUNCE_nwchem-users_emsl.pnl

Example input:

Title "acetate"

Start  acetate

echo

charge -1

geometry autosym units angstrom
 C     0.0191498     0.0215213     0.0191498
 H     -0.621688     -0.620669     0.658428
 H     0.658428     -0.620669     -0.621688
 H     -0.628475     0.649316     -0.628475
 C     0.881900     0.883055     0.881900
 O     1.74905     0.315740     1.74905
 O     0.799516     2.22959     0.799516
end

basis
* library "cc-pvtz"
end

dft
  mult 1
  direct
  noio
  XC b3lyp
  grid fine
  mulliken
end

driver
end

set vib:scalefreq  0.9854

task dft optimize
task dft freq

which gives:

 Temperature                      =   298.15K
 frequency scaling parameter      =   0.9854

 Zero-Point correction to Energy  =   29.486 kcal/mol  (  0.046990 au)
 Thermal correction to Energy     =   31.752 kcal/mol  (  0.050601 au)
 Thermal correction to Enthalpy   =   32.345 kcal/mol  (  0.051544 au)

 Total Entropy                    =   64.086 cal/mol-K
   - Translational                =   38.129 cal/mol-K (mol. weight =  59.0133)
   - Rotational                   =   23.739 cal/mol-K (symmetry #  =        1)
   - Vibrational                  =    2.218 cal/mol-K

 Cv (constant volume heat capacity) =   11.268 cal/mol-K
   - Translational                  =    2.979 cal/mol-K
   - Rotational                     =    2.979 cal/mol-K
   - Vibrational                    =    5.309 cal/mol-K

c.f.

 Temperature                      =   298.15K
 frequency scaling parameter      =   1.0000

 Zero-Point correction to Energy  =   29.923 kcal/mol  (  0.047686 au)
 Thermal correction to Energy     =   32.173 kcal/mol  (  0.051272 au)
 Thermal correction to Enthalpy   =   32.766 kcal/mol  (  0.052215 au)

 Total Entropy                    =   64.008 cal/mol-K
   - Translational                =   38.129 cal/mol-K (mol. weight =  59.0133)
   - Rotational                   =   23.739 cal/mol-K (symmetry #  =        1)
   - Vibrational                  =    2.141 cal/mol-K

 Cv (constant volume heat capacity) =   11.132 cal/mol-K
   - Translational                  =    2.979 cal/mol-K
   - Rotational                     =    2.979 cal/mol-K
   - Vibrational                    =    5.173 cal/mol-K