[gmx-users] energy units

[David van der Spoel]

On Sat, 2005-01-29 at 13:02 -0500, Ashish Gupta wrote:
> Hello gmx-users:
> 
>    I posted a question on the group sometime back but I think I made my 
> question too complicated to answer. So let me put it in a simpler way
> 
> The energy units are   (mass* length* length)/(time*time) . So for gromacs 
> it is   (amu *nm*nm )/(ps*ps) . Hence when gromacs reports total energy in 
> units of KJ/mol all I have to do to convert it to KJ is divide it by 
> Avogadro number. Please correct me if I am incorrect.
> 
> But then why does g_energy have -nmol (default value = 1) option with it. 
> Why do we have to specify the total number of molecules here since we can 
> always find the total energy of the sytem by dividing the energy reported in 
> KJ/mol by Avogadro number to get the total energy of the system in KJ.
> 
If you have mixtures it is not as simple. Therefore you have to do the
division by the number of molecules yourself.

> I am relatively new to gromacs and highly appreciate any help,
> Best Wishes,
> Ashish. 
> 
> 
> _______________________________________________
> gmx-users mailing list
> gmx-users at gromacs.org
> http://www.gromacs.org/mailman/listinfo/gmx-users
> Please don't post (un)subscribe requests to the list. Use the 
> www interface or send it to gmx-users-request at gromacs.org.
-- 
David.
________________________________________________________________________
David van der Spoel, PhD, Assoc. Prof., Molecular Biophysics group,
Dept. of Cell and Molecular Biology, Uppsala University.
Husargatan 3, Box 596,          75124 Uppsala, Sweden
phone:  46 18 471 4205          fax: 46 18 511 755
spoel at xray.bmc.uu.se    spoel at gromacs.org   http://xray.bmc.uu.se/~spoel
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

-- 
David.
________________________________________________________________________
David van der Spoel, PhD, Assoc. Prof., Molecular Biophysics group,
Dept. of Cell and Molecular Biology, Uppsala University.
Husargatan 3, Box 596,          75124 Uppsala, Sweden
phone:  46 18 471 4205          fax: 46 18 511 755
spoel at xray.bmc.uu.se    spoel at gromacs.org   http://xray.bmc.uu.se/~spoel
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++