Dear Dr van der Spoel

Thank you very much for your reply.
I made another simulation using your
top file and I found again the same pattern
for my distribution.

Could I be making some error when I m execute
the mk_angnmx and g_angle programs?

Ive been used:

mk_ndx -s topol.tpr -n angle.ndx -type ryckaert-bellemans

and at sequence

g_angle -f traj.xtc -s topol.tpr -n angle.ndx -od



Eudes Fileti wrote:
> Dear gmx users
> I have attemped to simulate a box of ethanol in normal conditions of
> temperature and pressure.
> I reproduced very well some literature data (as g(r)) however I had
> problems to reproduce the angular
> distribution function for the dihedral (C-C-O-H).
> This angle must have a peak in 180 degrees and two lesser (and
> symmetrical) peaks in 60 and 300 degrees (as shows the figure 1 of this
> link http://cbio.mskcc.org/~leonor/jpcb97.pdf ).
> However my distribution presents a maximum in 100 degrees with two (but
> not symmetrical) peaks the left.
> I already made almost everything:
> I used both, dihedral GROMACS and Ryckaert-Bellemans, I applied almost
> all the avaliables parameters
> (eg in ffoplsaabon.itp), I set nrexcl 2, 3, 4, 5, I remade the
> simulation several times in with differents conditions, but always I
> found the same pattern.
> Somebody already had some experience like that? If it had, could you
> give me a insight? Bellow I give my top file.
> Thank you in advance.
> eef


 

COpare to my attached one.

--
David.
________________________________________________________________________
David van der Spoel, PhD, Assoc. Prof., Molecular Biophysics group,
Dept. of Cell and Molecular Biology, Uppsala University.
Husargatan 3, Box 596,          75124 Uppsala, Sweden
phone:  46 18 471 4205          fax: 46 18 511 755
[EMAIL PROTECTED]    [EMAIL PROTECTED]    http://folding.bmc.uu.se
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-------------- next part --------------
;
; Ethanol, Jorgensen et al. JACS 118 pp. 11225 (1996)
;
[ moleculetype ]
; name  nrexcl
ETH     3

[ atoms ]
;   nr    type   resnr  residu    atom    cgnr        charge          mass
     1       opls_157       1     ETH       C       1   -0.18
     2       opls_156       1     ETH       H       1   0.06
     3       opls_156       1     ETH       H       1   0.06
     4       opls_156       1     ETH       H       1   0.06
     5       opls_157       1     ETH       C       2   0.145
     6       opls_156       1     ETH       H       2   0.06
     7       opls_156       1     ETH       H       2   0.06
     8       opls_154       1     ETH      OA       2   -0.683
     9       opls_155       1     ETH      HO       2   0.418

[ bonds ]
;  ai    aj funct           c0           c1
1      5       1
3      1       1
4      1       1
2      1       1
7      5       1
6      5       1
8      5       1
9      8       1

[ pairs ]
; i    j       func
2      6
2      7
2      8
3      6
3      7
3      8
4      6
4      7
4      8
1      9
6      9
7      9

[ angles ]
;  ai    aj    ak funct           c0        c1
; H3
2      1       5       1
3      1       5       1
4      1       5       1
;
4      1       3       1
4      1       2       1
;
3      1       2       1
;
1      5       7       1
1      5       6       1
1      5       8       1
;
5      8       9       1
;
6      5       7       1
6      5       8       1
;
7      5       8       1

;
[ dihedrals ]
2      1       5      8        3
3      1       5      8        3
4      1       5      8        3
1      5       8      9        3
6      5       8      9        3
7      5       8      9        3

______________________________________
                                      Eudes Eterno Fileti
          Centro de Ciência Naturais e Humanas
                        Universidade Federal do ABC
                                  Rua Santa Adélia, 166
                                            CEP 09210-170
                                               skype: eefileti
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