[gmx-users] Problem force constant bond stretc.

[Paolo Costa]

Thanks a lot.

Best regards,

Paolo

Il giorno gio 16 apr 2020 alle ore 07:57 David van der Spoel <
spoel at xray.bmc.uu.se> ha scritto:

> Den 2020-04-15 kl. 23:48, skrev Paolo Costa:
> > Dear Gromacs users,
> >
> > I have a problem regarding force constant for bond stretching. By
> employing
> > VFFDT software, I got C-C bond stretching force constant (for Benzene,
> > B3LYP-6311++G*) equal to 383.23 kcal/ (mol A^2) which is equivalent to
> > 160343 kj/ (mol nm^2). However when I look to the ffbonded.itp file of
> > Amber99.ff the CA-CA force constant value is 392459.2  kj/ (mol nm^2). It
> > seems that the value I got from VFFDT is somehow half than the one
> reported
> > in Amber force field.
> > Can somebody help me to figure out such issue?
> >
> > Thanks a lot in advance for your help.
> >
> Vbond = (k/2) (r - r0)^2
>
> Some methods do not use the division by two, so it can be a matter of
> definition.
>
> --
> David van der Spoel, Ph.D.,
> Professor of Biology
> Uppsala University.
> http://virtualchemistry.org
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-- 
Paolo Costa, Ph.D.
Postdoctoral Researcher
Department of Chemistry and Biomolecular Sciences
University of Ottawa
10 Marie Curie, Ottawa, ON K1N 6N5, Canada
Room number: DRO 326 (D'Iorio Hall)