MOLPRO

43 VIBRATIONAL FREQUENCIES (FREQUENCIES) 337
43.8 Thermodynamical properties (THERMO)
It is also possible to calculate the thermodynamical properties of the molecule. Since MOLPRO
can only handle Abelian point groups it is necessary to give the point group of the molecule in
the input file:
THERMO,[SYM=pointgroup],[TEMP=value], [PRESS=value], [TMIN=value, TMAX=value, TSTEP=value]
pointgroup has to be the Schoenflies Symbol (e.g. C3v for ammonia; linear molecules have
to be C*v or D*h respectively). If no point group is given, the point group is determined
automatically, but only Abelian groups (D2H and subgroups) are recognized. If the molecule
has higher symmetry this may eventually cause deviations in the rotational entropy.
The temperature (in K), pressure (in atm) or a range of temperatures (in K) can be given as
options.
If no temperature or pressure is specified the zero-point vibrational energy and the enthalpy
H(T ) − H(0) [kJ/mol], heat capacity C v [J/mol K] and entropy S [J/mol K] are calculated for
standard temperature and pressure (T = 298.150 [K], p = 1 [atm]).
The FREQUENCIES program sets the variable ZPE containing the zero-point-energy of the
harmonic vibrations in atomic units. If the THERMO option is used, the variables HTOTAL and
GTOTAL, containing the enthalpy and the free enthalpy of the system in atomic units, are also
set.
43.9 Examples
***,formaldehyde freqency calculation
memory,8,m
basis=vdz
gthresh,energy=1.d-8
geomtyp=xyz
symmetry,nosym
geometry={
4
FORMALDEHYDE
C 0.0000000000 0.0000000000 -0.5265526741
O 0.0000000000 0.0000000000 0.6555124750
H 0.0000000000 -0.9325664988 -1.1133424527
H 0.0000000000 0.9325664988 -1.1133424527
}
hf;accu,14
optg;coord,3n;
{frequencies,analytic
thermo,sym=c2v
print,thermo}
mp2
optg;coord,3n
{frequencies
thermo,sym=c2v
print,thermo}
http://www.molpro.net/info/current/examples/form_freq.com