[gmx-users] More dihedral doubts

Jones de Andrade johannesrs at gmail.com
Sun Jul 29 20:04:55 CEST 2007


Hi all again.

Sorry for bothering all you with this dihedrals subject.

Well, I'm trying this in my .itp file:

**************************************************************
[ dihedraltypes ]
;  i     j     k     l     funct    phi (degree)      cp
(kJ/mol.rad^2)       mult(n)
   CT    CT    NT    CT    1          0.00             1.25520
3.0  ;amber99
   CT    CT    NT    CT    1        180.00             2.00832
2.0  ;amber99
   X     CT    NT    X     1          0.00             1.25520
3.0  ;amber99             ;padrao
   CT    CT    CT    CT    1          0.00             0.75312
3.0  ;amber99
   CT    CT    CT    CT    1        180.00             1.04600
2.0  ;amber99
   CT    CT    CT    CT    1        180.00             0.83680
1.0  ;amber99
   F     CT    CT    F     1          0.00             0.0000
3.0  ;amber99
   F     CT    CT    F     1        180.00             5.20800
1.0  ;amber99
   X     CT    CT    X     1          0.00             0.6530
3.0  ;amber original e 99 ;padrao
********************************************************************

But I just found that grompp is yelding this for me:

**********************************************************************
processing topology...
WARNING 1 [file "../top/ff_amber_perF.itp", line 62]:
  Overriding Proper Dih. parameters,
  old: 0 1.2552 3 0 0 0
  new: CT CT NT CT 1 180.00 2.00832 2.0

WARNING 2 [file "../top/ff_amber_perF.itp", line 65]:
  Overriding Proper Dih. parameters,
  old: 0 0.75312 3 0 0 0
  new: CT CT CT CT 1 180.00 1.04600 2.0

WARNING 3 [file "../top/ff_amber_perF.itp", line 66]:
  Overriding Proper Dih. parameters,
  old: 180 1.046 2 0 0 0
  new: CT CT CT CT 1 180.00 0.83680 1.0

WARNING 4 [file "../top/ff_amber_perF.itp", line 68]:
  Overriding Proper Dih. parameters,
  old: 0 0 3 0 0 0
  new: F CT CT F 1 180.00 5.20800 1.0
*******************************************************************

What does it mean? What kind of mistake am I doing? Am I wrong, or
definitelly gromacs still doesn't support multiple trigonometric dihedral
potentials and then I really need to transform it on a RB-potential (and the
reference I found on a web site is wrong)?

Thanks a lot in advance... Any help would be really welcome.  :)

Sincerally yours,

Jones
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