rotating constraints constant

From: himanshu chandola (
Date: Wed Mar 03 2004 - 02:12:34 CST

hello everyone -
Perhaps somebody has an idea about this problem!
I need to use rotating constraints - but the stiffness constant for the
force applied has units of kcal/mol/A*A . Now i need around 10 N/m
stiffness constant. These two units have a conversion factor of around
10exp(23). Now this means that when i write 10N/m in my configuration file
it has to be something very small. My questions are:

1. why the units used in the conf files so large(for stiffness constant)?
2. if i need to write my 10N/m in terms of the units used by namd - Is it
sure that namd inputs the stiffness constant as a double so that my low
value of stiffness constant is inputted and is it okay if i put it as
(SOME NUMBER)*10exp(-23). If not then what?

Those who've used rotating constraints featured are requested to kindly
put their ideas here.

with kind regards,


Morpheus: Do you believe in fate, Neo?
Neo: No.
Morpheus: Why Not?
Neo: Because I don't like the idea that I'm not in control of my life.

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