Gaussian 03 Online Manual
Last update: 29 September 2006
freqchk
The freqchk utility is used to retrieve frequency and thermochemistry data from a checkpoint file, with optional specification of an alternate temperature, pressure, scale factor, and/or isotope substitutions.
freqchk can prompts for all other information that it requires. The following annotated sessions illustrate its use in this mode (user input is set in boldface type):
$ freqchk
Checkpoint file? solvent.chk
Write Hyperchem files? n
Temperature (K)? [0=>298.15] 0 Zero must be entered; return doesn't work
Pressure (Atm)? [0=>1 atm] 0
Scale factor for frequencies during thermochemistry? [0=>1/1.12] 0
Do you want the principal isotope masses? [Y]: Return accepts defaults
Isotopes for each atom are printed
Full mass-weighted force constant matrix:
Low frequencies --- -948.3077 .0008 .0020 .0026
...
Normal Gaussian frequency output follows ...
1 2
?A ?A
Frequencies -- 1885.3939 3853.5773
Red. masses -- 1.0920 1.0366
Frc consts -- 2.2871 9.0697
IR Inten -- 17.3416 21.5997
Raman Activ -- 7.8442 67.0384
Depolar -- .7428 .2248
Atom AN X Y Z X Y Z Normal modes
1 8 .06 .00 .04 .04 .00 .02
2 1 -.70 .00 .03 .01 .00 -.71
...
-------------------
- Thermochemistry -
-------------------
Temperature 298.150 Kelvin. Pressure 1.00000 Atm.
Thermochemistry will use frequencies scaled by .8929.
...
Zero-point vibrational energy 53494.5 (Joules/Mol)
12.78550 (Kcal/Mol)
VIBRATIONAL TEMPERATURES: 2422.01 4950.36 5495.38 (KELVIN)
Zero-point and thermal corrections:
Zero-point correction= .020375 (Hartree/Particle)
Thermal corr to Energy= .023210
Thermal corr to Enthalpy= .024154
Thermal corr to Gibbs Free Energy= .045589
E=thermal energy; CV=constant volume molar heat capacity; S=entropy
E CV S
KCAL/MOL CAL/MOL-KELVIN CAL/MOL-KELVIN
TOTAL 14.564 6.001 45.114
ELECTRONIC .000 .000 .000
TRANSLATIONAL .889 2.981 34.609
ROTATIONAL .889 2.981 10.500
VIBRATIONAL 12.787 .039 .005
Partition functions
Q LOG10(Q) LN(Q)
TOTAL BOT .561443D-01 -1.250695 -2.880127
TOTAL V=0 .132155D+09 8.121085 18.699192
VIB (BOT) .424961D-09 -9.371650 -21.579023
VIB (V=0) .100030D+01 .000129 .000297
ELECTRONIC .100000D+01 .000000 .000000
TRANSLATIONAL .300436D+07 6.477751 14.915574
ROTATIONAL .439749D+02 1.643204 3.783618
$ freqchk solvent.chk Checkpoint filename can be placed on the command line
Write Hyperchem files? n
Temperature (K)? [0=>298.15] 300 Alternate temperature
Pressure (Atm)? [0=>1 atm] 1.5 Alternate pressure
Scale factor for freqs during thermochem? [0=>1/1.12] 1 No scaling
Do you want to use the principal isotope masses? [Y]: n
For each atom, give the integer mass number.
In each case, the default is the principal isotope.
Atom number 1, atomic number 8: [16] Return accepts default
Atom number 2, atomic number 1: [1] 2 Specify isotope masses as integers
...
Frequency output follows, reflecting the values specified above. Note that if scaling is specified, only the thermochemistry data reflects it; the frequencies themselves are not scaled.
Alternatively, you can specify all freqchk input on the command line, as in this example, which performs the same operation as the final interactive session above:
$ freqchk solvent.chk N 300 1.5 1 N
You will be prompted for the isotopes if the final parameter is N.