freeh - differences in ZPE

[yasmeen]

I've recently performed some calculations using freeh in order to obtain termochemical properties some small organic molecules eg. 1-phenylethanol and I am cofused about differences in calculated ZPE in Turbomole and Tmolex.

I mean, e.g.,  for 1-phenylethanol in aoforce.out file ZPE = 0.1606899 Hartree.
Using freeh module in Turbomole I get ZPE = 418.3 kJ/mol, but when I calculate the same (all input files are the same) in TmoleX I get ZPE = 421.9 kJ/mol (what in fact equals 0.1606899 Hartree).

Other values are also different:

chemical potential = 337,97 kJ/mol (TM) or 341.71 kJ/mol (TX)
energy = 437.75 kJ/mol (TM)  vs  441.26 kJ/mol (TX)

Entropy value is the same in both cases.


Could anyone explain me where these differences come from and which of them are correct? I'd be grateful.

[uwe]

Hi,

did you use a scaling factor for the frequencies in freeh?

Regards,

Uwe

[yasmeen]

Hi,

Thank you for your post. To tell the truth I used all default parameters, including a scaling factor,  suggested by freeh.

Regards,
Agnieszka

[uwe]

Hi,

the (old) freeh still suggests the scaling factor for Hartree-Fock as default while the (new) option in TmoleX sets the scaling factor to one as default. If you accepted both defaults, this might be the reason for the different results.

Regards,

Uwe

[yasmeen]

Thank you very much!