X-plor questions

Tina Marie Conti gt5337a at prism.gatech.edu
Wed Jan 28 16:40:10 EST 1998


Hello

I am very new to x-plor so the following questions may seem quite basic
but any help is greatly appreciated.

1)  I am trying to set up PICK statements to get an output of specified
dihedral angles.  The statement I set up looks like:
PICK DIHEdral
	(atom 1)
	(atom 2)
	(atom 3)
	(atom 4)
	geometry
The same lines appear in the log file but the angle is not listed.  I
assume maybe I need a print statement but have no idea how to set it up.
Any help?

2)  I have 5 print statements set up for various parameters.  All seem to
work except the one that prints cdih violations (the syntax follows the
statements that work so I don't really know what the problem is).  I have
set the threshold to zero and I still do not get any violations (although
when I measure the angles manually, most are significantly different from
the input equilibrium angle).  Any ideas? (I should mention that the file
listing the dihedral angle restraints is read without error, but the
E(cdih) value is consistenly zero, and I have included cdih in the flag
statement).

3)  This last question may be too much to answer without my input file but
here it is:  The energy minimization never converges.  I have set nsteps
to 3000 and the lowest grad I have gotten is around 0.18.  I have tried
breaking down the minimization into 10 x 200 (for example) as was
suggested previously but there is still no convergence.  Any ideas?

Again, I appreciate any help and apologize if the questions are
simplistic.

Tina Davis



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