[gmx-users] g_gyrate

[Dmitriy Golubobsky]

>
>
> >
> > ---------- Пересланное письмо ----------
> > From: David van der Spoel <spoel at xray.bmc.uu.se>
> > To: Discussion list for GROMACS users <gmx-users at gromacs.org>
> > Date: Fri, 26 Jan 2007 10:02:01 +0100
> > Subject: Re: [gmx-users] g_gyrate
> > Dmitriy Golubobsky wrote:
> > > Dear Gurus,
> > > I've got question on Radius of gyrtion calculation.
> > > my system consists of 1 polymer and a solvent.
> > > I did MD and decide to calculate Rg for this system
> > > I made index group consisting my residues
> > > g_gyrate -f xtc_file -s tpr_file -n ndx_file -p -o xvg_output
> > > ok. I've got the output file with 4 colums: time Rg Rx Ry Rz
> > > I use -p option to get components in principal axes, because I' d like
> >
> > > to calculate form-factors for my system.
> > >
> > > as I undersand Rg = sqrt ( sum_{i}^{N} r_i*m_i)/M)
> > > ok. then fx=Rx/Rg^2, fy=Ry/Rg^2, fz=Rz/Rg^2
> > > and I  wish to get fx+fy+fz=1 but it is not so.
> > > where I'm mistaken?
> > > How does components Rxyz in principal axes are calculated?
> > > I'm using gromacs 3.3.1
> > > Thanks a lot.
> > Rg = sqrt ( sum_{i}^{N} (r_i^2)*m_i)/M)
>
>

This question can be asked on momet of inertia too.
if I'm calculating moment of ineria in pricipal axes.
is it possible to diagonialize tenzor of inertia? and to get it components?
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