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Re^2: dipole moment, Dear Alex,, Many thanks! It worked!, All the best!, Mihai

Mihai Medeleanu
mihai.medeleanu@upt.ro


On Fri Nov 20 '15 3:06pm, Alex Granovsky wrote
----------------------------------------------
>Dear Mihai,

>the dipole moment of a charged system is not uniquely defined.
>It depends on the choice of a coordinate system.

>During optimization/saddle point location/hessian runs
>Firefly always computes dipole moment using the origin of
>an input coordinate system i.e. at the point with (0,0,0)
>coordinates.

>To compute dipole moment at the center of mass coordinates,
>extract the desired geometry and run runtyp=energy run, adding
>the following to your input:

>

 $ELMOM  IEMOM=1 where=comass $END

>Hope this helps.

>Kind regards,
>Alex Granovsky
>
>
>
>
>On Wed Nov 18 '15 6:24pm, Mihai Medeleanu wrote
>-----------------------------------------------
>>Hello Firefly users!

>>I have the following problem: when I compute the dipole moment for protonated amines (for instance methylammonium cation) I obtain a value ten times greater than with GAMESS-US or other quantum chemistry program. For the mentioned compound Firefly (8.1.1) gave me 15.5157 Debye (which in any case is a too big value!). For non-protonated amines the results are OK (same results on both programs). I used DFT B3LYP 6-31G.
>>Data for methylammonium cation:

>>!   File created by the GAMESS Input Deck Generator Plugin for Avogadro
>> $BASIS GBASIS=N31 NGAUSS=6 NDFUNC=1 NPFUNC=1 $END
>> $CONTRL SCFTYP=ROHF RUNTYP=OPTIMIZE DFTTYP=B3LYP MULT=1 ICHARG=1 $END
>> $STATPT OPTTOL=0.0001 NSTEP=20 $END

>> $DATA
>>maH
>>C1
>>C     6.0    -4.04405     1.60919    -0.01255
>>N     7.0    -2.50801     1.70111     0.00782
>>H     1.0    -4.43069     0.72487    -0.54256
>>H     1.0    -4.44207     2.50496    -0.50704
>>H     1.0    -4.43860     1.59341     1.01009
>>H     1.0    -2.05318     1.66836    -0.91632
>>H     1.0    -2.04559     0.90265     0.50765
>>H     1.0    -2.14817     2.57106     0.42741
>> $END

>>


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