Mihai Medeleanu
mihai.medeleanu@upt.ro
>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
>>