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MMFP: gaussian restraint function for dihedral
#33353 01/25/14 10:51 PM
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jeffrey Offline OP
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Dear all,

Can CHARMM restrain the dihedral using gaussian function in MMFP?

Many thanks for your information.

Best,

Jeff Yang

Re: MMFP: gaussian restraint function for dihedral
jeffrey #33354 01/26/14 10:00 AM
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Yes,according to mmfp.doc it should be possible.


Lennart Nilsson
Karolinska Institutet
Stockholm, Sweden
Re: MMFP: gaussian restraint function for dihedral
jeffrey #33355 01/26/14 06:15 PM
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Although I've found MMFP to be quite useful, I've also found it prudent to test my assumptions about how it works and what it's doing.

For example, I once thought that INSIDE and OUTSIDE keywords might work with PLANAR restraints, using the plane normal to distinguish in from out, such that the potential would only apply on one side of the plane. My tests indicated that was incorrect; instead, I discovered that DROFF could be used to create a "flat" region where the potential did not apply, centered about the plane.


Rick Venable
computational chemist

Re: MMFP: gaussian restraint function for dihedral
rmv #33356 01/27/14 12:50 AM
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jeffrey Offline OP
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I tested the combination btw GAUSSIAN and dihe. The program stopped at the error message:

---------
MMFP> GEO sphere symm gaussian p1 1.2 droff -110.0 -
MMFP> force 1.2 -
MMFP> select atom pra 1 c7 end dihe select atom pra 1 c6 end -
MMFP> select atom pra 1 c5 end select atom pra 1 c3 end
GEO INITIALIZED, MAXGEO= 50
Sphere constraint
Dihedral constraint
Gaussian constraint

***** LEVEL -1 WARNING FROM MMFP> *****
***** FUNCTION NOT COMPATIBLE WITH ANGLE/DIHEDRAL CONSTRAINT
******************************************
-------------

It seems that CHARMM doesn't support this common combination currently.

Best,

Jeff Yang


Moderated by  BRBrooks, lennart, rmv 

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