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OPTIMIZATION



Modellers:

When setting up an optimization, how does one define a different number
of iterations for the conjugate graidents and MD stages?

In one of the scripts provided with the program I see the variable: 
SET MAX_VAR_ITERATIONS = 500

..which I presume sets the number of iterations for the CG stage - so is
there a corresponding variable MAX_??_ITERATIONS for MD stage? or does
setting MAX_ITERATIONS set the number of MD iterations?

i.e. will..

SET MAX_VAR_ITERATIONS = 500
SET MAX_ITERATIONS = 1000

..in my modelling script do 500 steps of CG followed by 1000 steps of
MD?  I see no note of MAX_VAR_ITERATIONS in the Index..

also, is it common to SET MD_RETURN = MINIMAL, or to FINAL?  I presume
MINIMAL?

Further, in the default _model script is equilibration (INIT_VELOCITIES)
set to ON?  In the _defs script it is not defined, so is it on by
default, and what effect may this have on optimization?

Last, what effect does running the MD stage at high temperatures have on
the model? Presumably, more conformational space is sampled, and if the
MINIMAL model is chosen, perhaps this may be of lower PDF than if a
lower temperature was chosen?

Thanks in advance,

Nick


____________________

Nicholas Glover
Department of Chemistry
Simon Fraser University
8888 University Drive
Burnaby, BC
V5A 1S6
Canada
 
Tel: (604) 291-4531
Fax: (604) 291-3765

email: