AMBER: Using ntr=1 in xleap

From: Lili Peng <>
Date: Fri, 31 Aug 2007 14:27:44 -0700

Hi all,

I'm having problems running a two-fold minimization procedure on a
20-residue polyglutamic acid structure. I'd like to 1) minimize the solvent
(TIP3PBOX) while keeping the polypeptide fixed and 2) minimize the entire
system. However, in my initial minimization of solvent, I run into the
error "Unit 10 Error on open: refc". I'm pretty sure the error has to do
with my setting ntr=1, because when i turn ntr off (=0), Sander executes the
minimization smoothly.

My input line for running Sander is: "/sander.1cpu -O -i
-o min_classical.out -p GLU20_alpha.prmtop GLU20_.inpcrd -r

My minimization script is the following:

"Initial minimization of solvent
 imin=1, maxcyc=200, ncyc=50, ntpr=10,
 cut=8.0, ntb=1, ntc=2,
 ntr=1, restraintmask=':1-20',

Does anyone know what could the problem?



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Received on Sun Sep 02 2007 - 06:07:37 PDT
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