[Chimera-users] constraints and restraints

Elaine Meng meng at cgl.ucsf.edu
Tue Mar 2 16:54:55 PST 2010

The Chimera release notes describe what is new or changed in a release:
... clicking the "1.4" link:

The meaning of "constraint" "restraint" and "tether" may change based  
on which program you are using.  Each program should explain it in its  
own documentation.  In programs I've used, "constraints" meant atoms  
are completely fixed in place (frozen, cannot move) whereas  
"restraints" use a force constant like a spring, and allowed some  
movement.  I don't have any opinion on the technical definition of  
"tethering."  Again, don't rely on my descriptions as final because  
different programs may use the words to mean different things.

Chimera minimization only allows "fixing" some of the atoms so they  
can't move at all.  It does not  allow holding atoms in place with  
force constants.

I hope this helps,
Elaine C. Meng, Ph.D.                          meng at cgl.ucsf.edu
UCSF Computer Graphics Lab and Babbitt Lab
Department of Pharmaceutical Chemistry
University of California, San Francisco

> nice to give you a letter!
>  is there a new one ,really?
> what is the new feature in the least software?
> I want constraint ,restraint and tether some atoms and backbone.
> how can I do constraiting ,restrainting and tethering in  
> software.how can i set value for constraiting ,restrainting and  
> tethering.
> what is the difference between them?
> thank you!

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