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Re^2: Interpreting thermochemical output

Adebayo A. Adeniyi
a.aadeniyi@yahoo.com


Thanks Prof. Dr Pavel,

The link is really helpful.


On Wed Oct 10 '12 7:17pm, Solntsev Pasha wrote
----------------------------------------------
>On Wed Oct 10 '12 4:21pm, Adebayo A. Adeniyi wrote
>--------------------------------------------------
>>Dear Firefly Users,

>>Please, I am trying to get the total energy, enthalpy, gibbs free energy of my system. I compute the thermochemical properties of simple molecule "H2O" but I am confused because I obtained two thermochemical output as follows:

>>  THERMOCHEMISTRY AT T=  298.15 K
>>     -------------------------------

>> USING IDEAL GAS, RIGID ROTOR, HARMONIC NORMAL MODE APPROXIMATIONS.
>> P=  1.01325E+05 PASCAL.
>> ALL FREQUENCIES ARE SCALED BY   1.00000
>> THE MOMENTS OF INERTIA ARE (IN AMU*BOHR**2)
>>         2.07890        4.38535        6.46425
>> THE ROTATIONAL SYMMETRY NUMBER IS  1.0
>> THE ROTATIONAL CONSTANTS ARE (IN GHZ)
>>    867.32830   411.16213   278.93251
>> THE HARMONIC ZERO POINT ENERGY IS (SCALED BY   1.000)
>>        0.021773 HARTREE/MOLECULE     4778.512983 CM**-1/MOLECULE
>>       13.662468 KCAL/MOL               57.163766 KJ/MOL

>>               Q               LN Q
>> ELEC.     1.00000E+00       0.000000
>> TRANS.    3.00431E+06      14.915558
>> ROT.      8.68998E+01       4.464756
>> VIB.      1.00017E+00       0.000170
>> TOT.      2.61118E+08      19.380484

>>              E         H         G         CV        CP        S
>>           KJ/MOL    KJ/MOL    KJ/MOL   J/MOL-K   J/MOL-K   J/MOL-K
>> ELEC.      0.000     0.000     0.000     0.000     0.000     0.000
>> TRANS.     3.718     6.197   -36.975    12.472    20.786   144.800
>> ROT.       3.718     3.718   -11.068    12.472    12.472    49.593
>> VIB.      57.167    57.167    57.163     0.106     0.106     0.014
>> TOTAL     64.604    67.083     9.121    25.050    33.364   194.407

>>              E         H         G         CV        CP        S
>>         KCAL/MOL  KCAL/MOL  KCAL/MOL CAL/MOL-K CAL/MOL-K CAL/MOL-K
>> ELEC.      0.000     0.000     0.000     0.000     0.000     0.000
>> TRANS.     0.889     1.481    -8.837     2.981     4.968    34.608
>> ROT.       0.889     0.889    -2.645     2.981     2.981    11.853
>> VIB.      13.663    13.663    13.662     0.025     0.025     0.003
>> TOTAL     15.441    16.033     2.180     5.987     7.974    46.464
>> ......END OF NORMAL COORDINATE ANALYSIS......

>>How do I get the total E, H, G ? I suppose the E should be the FINAL ENERGY which is -75.5859597519 in the output file. What does "Q" and "LN Q" stands for ?

>Q is  partition function. You can read any textbook about statistical thermodynamic or, for example, check this link: http://www.gaussian.com/g_whitepap/thermo.htmhttp://www.gaussian.com/g_whitepap/thermo.htm

>Pavel.
>
>
>
>>Thanks.


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