I note that in Nmode, the equivalent test is against 1.d0,
is that what Sander should switch to?
jim
On Mon, 2004-06-14 at 18:08, David A. Case wrote:
> On Mon, Jun 14, 2004, James W. Caldwell wrote:
>
> > I setup a simple test: F-O-F, linear, with a linear force constant.
> > the angle energy should be zero, right? well it's 0.2 kcal/mole
> > in both sander7 and sander8. I've attached a tar file with an input,
> > prmtop, prmcrd and the sander8 output.
> >
>
> See the code around line 416 of ene.f, and consider changing "pt999"
> to something closer to unity. Note that acos(-0.999) is 177.4 degrees,
which
> is significantly from 180. There is a nasty problem involved in getting
> good forces with linear bond angles. Someone should plunge in and fix
the
> code (similar problems arise with linear angles in ephi.f). I have a
> vague recollection that moil does this "correctly", so that might be
worth
> checking....
>
> ...dac
>
> --
>
> ==================================================================
> David A. Case | e-mail: case.scripps.edu
> Dept. of Molecular Biology, TPC15 | fax: +1-858-784-8896
> The Scripps Research Institute | phone: +1-858-784-9768
> 10550 N. Torrey Pines Rd. | home page:
> La Jolla CA 92037 USA | http://www.scripps.edu/case
> ==================================================================
--
James W. Caldwell 650-724-5322
Department of Chemistry
Clark Center, S2.2, Rm S294
Stanford University
Stanford, CA 94305-5447
Received on Wed Apr 05 2006 - 23:50:01 PDT
