[gmx-users] Need to confirm parameters.

Sailesh Bataju thelaven at gmail.com
Mon May 22 16:01:25 CEST 2017


Hi Sir,

Right, CHARMM force field is what I'm looking for. Thank you very much
sir for your advice. I've made parameter file of isobutane using
CHARMM36 force field files shown below so I've a few questions
regarding it.

[ defaults ]
; nbfunc	comb-rule	gen-pairs	fudgeLJ	fudgeQQ
  1		        1		    yes		    1.0	    1.0

[ atomtypes ]
;   name  at.num   mass        charge     ptype       sigma         epsilon
   CC31A     6    12.011000   -0.090        A       0.356359487256  0.13389
   CC33A     6    12.011000   -0.270        A       0.363486677001  0.32635
   HCA1A     1     1.008000    0.090        A       0.238760856462  0.18828
   HCA3A     1     1.008000    0.090        A       0.238760856462  0.10042

[ moleculetype ]
; Name            nrexcl
isobutane           3

[ atoms ]
;   nr      type    resnr   residue     atom    cgnr    charge  mass
typeB    chargeB      massB
; residue   1 IBUT rtp IBUT q  0.0
    1       CC33A   1       IBUT        C1      1       -0.270  ; qtot
-0.270
    2       HCA3A   1       IBUT        H2      2        0.090  ; qtot -0.180
    3       HCA3A   1       IBUT        H3      3        0.090  ; qtot -0.090
    4       HCA3A   1       IBUT        H4      4        0.090  ; qtot  0.000
    5       CC31A   1       IBUT        C5      5       -0.090  ; qtot -0.090
    6       HCA1A   1       IBUT        H6      6        0.090  ; qtot  0.000
    7       CC33A   1       IBUT        C7      7       -0.270  ; qtot -0.270
    8       HCA3A   1       IBUT        H8      8        0.090  ; qtot -0.180
    9       HCA3A   1       IBUT        H9      9        0.090  ; qtot -0.090
    10      HCA3A   1       IBUT        H10     10       0.090  ; qtot  0.000
    11      CC33A   1       IBUT        C11     11      -0.270  ; qtot -0.270
    12      HCA3A   1       IBUT        H12     12       0.090  ; qtot -0.180
    13      HCA3A   1       IBUT        H13     13       0.090  ; qtot -0.090
    14      HCA3A   1       IBUT        H14     14       0.090  ; qtot  0.000

[ bonds ]
:   ai  aj  funct   b0(nm)          kb[KJ mol^(-1) nm^(-2)]     ; 13 bonds
    1   2   1       0.11110000      269449.60
    1   3   1       0.11110000      269449.60
    1   4   1       0.11110000      269449.60               ;
         C13
    1   5   1       0.15380000      186188.00               ;
         |
    5   6   1       0.11110000      258571.20               ;
    H14--C11--H12
    5   7   1       0.15380000      186188.00               ;
         |
    5   11  1       0.15380000      186188.00               ;
     H2  |   H8
    7   8   1       0.11110000      269449.60               ;
     |   |   |
    7   9   1       0.11110000      269449.60               ;
 H3--C1--C5--C7--H9
    7   10  1       0.11110000      269449.60               ;
     |   |   |
    11  12  1       0.11110000      269449.60               ;
     H4  H6  H10
    11  13  1       0.11110000      269449.60               ;
    11  14  1       0.11110000      269449.60

[ pairs ]
;    ai     aj     funct    ; 27 pairs
     1      8      1
     1      9      1
     1     10      1
     1     12      1
     1     13      1
     1     14      1
     2      6      1
     2      7      1
     2     11      1
     3      6      1
     3      7      1
     3     11      1
     4      6      1
     4      7      1
     4     11      1
     6      8      1
     6      9      1
     6     10      1
     6     12      1
     6     13      1
     6     14      1
     7     12      1
     7     13      1
     7     14      1
     8     11      1
     9     11      1
    10     11      1

[ angles ]
;  ai   aj  ak  funct   theta0(deg)     ktheta(KJ mol^(-1) rad^(-2))
     ub0(nm)          kub(KJ mol^(-1) nm^(-2)) ; 24 angles
    2   1   3   5       108.400000      297.064000
     0.18020000       4518.72    ; HCA3A-CC33A-HCA3A
    2   1   4   5       108.400000      297.064000
     0.18020000       4518.72
    3   1   4   5       108.400000      297.064000
     0.18020000       4518.72
    8   7   9   5       108.400000      297.064000
     0.18020000       4518.72
    8   7   10  5       108.400000      297.064000
     0.18020000       4518.72
    9   7   10  5       108.400000      297.064000
     0.18020000       4518.72
    12  11  13  5       108.400000      297.064000
     0.18020000       4518.72
    12  11  14  5       108.400000      297.064000
     0.18020000       4518.72
    13  11  14  5       108.400000      297.064000
     0.18020000       4518.72
    5   1   2   5       110.100000      279.742240
     0.21790000       18853.10   ; CC31A-CC33A-HCA3A
    5   1   3   5       110.100000      279.742240
     0.21790000       18853.10
    5   1   4   5       110.100000      279.742240
     0.21790000       18853.10
    5   7   8   5       110.100000      279.742240
     0.21790000       18853.10
    5   7   9   5       110.100000      279.742240
     0.21790000       18853.10
    5   7   10  5       110.100000      279.742240
     0.21790000       18853.10
    5   11  12  5       110.100000      279.742240
     0.21790000       18853.10
    5   11  13  5       110.100000      279.742240
     0.21790000       18853.10
    5   11  14  5       110.100000      279.742240
     0.21790000       18853.10
    7   5   6   5       110.100000      288.696000
     0.21790000       18853.10   ; CC33A-CC31A-HCA1A
    1   5   6   5       110.100000      288.696000
     0.21790000       18853.10
    11  5   6   5       110.100000      288.696000
     0.21790000       18853.10
    1   5   7   5       114.000000      446.432800
     0.25610000        6694.40   ; CC33A-CC31A-CC33A
    1   5   11  5       114.000000      446.432800
     0.25610000        6694.40
    11  5   7   5       114.000000      446.432800
     0.25610000        6694.40

[ dihedrals ]
;   ai    aj    ak    al    funct   phi0(deg)   kphi(KJ mol^(-1))
mult     ; 27 dihedrals
    2     1     5     6     9       0.000000     0.836800            3
     ; HCA1A-CC31A-CC33A-HCA3A
    2     1     5     7     9       0.000000     0.836800            3
     ; CC33A-CC31A-CC33A-HCA3A
    2     1     5    11     9       0.000000     0.836800            3
     ; CC33A-CC31A-CC33A-HCA3A
    3     1     5     6     9       0.000000     0.836800            3
     ; HCA1A-CC31A-CC33A-HCA3A
    3     1     5     7     9       0.000000     0.836800            3
     ; CC33A-CC31A-CC33A-HCA3A
    3     1     5    11     9       0.000000     0.836800            3
     ; CC33A-CC31A-CC33A-HCA3A
    4     1     5     6     9       0.000000     0.836800            3
     ; HCA1A-CC31A-CC33A-HCA3A
    4     1     5     7     9       0.000000     0.836800            3
     ; CC33A-CC31A-CC33A-HCA3A
    4     1     5    11     9       0.000000     0.836800            3
     ; CC33A-CC31A-CC33A-HCA3A
    1     5     7     8     9       0.000000     0.836800            3
     ; CC33A-CC31A-CC33A-HCA3A
    1     5     7     9     9       0.000000     0.836800            3
     ; CC33A-CC31A-CC33A-HCA3A
    1     5     7    10     9       0.000000     0.836800            3
     ; CC33A-CC31A-CC33A-HCA3A
    6     5     7     8     9       0.000000     0.836800            3
     ; HCA1A-CC31A-CC33A-HCA3A
    6     5     7     9     9       0.000000     0.836800            3
     ; HCA1A-CC31A-CC33A-HCA3A
    6     5     7    10     9       0.000000     0.836800            3
     ; HCA1A-CC31A-CC33A-HCA3A
   11     5     7     8     9       0.000000     0.836800            3
     ; CC33A-CC31A-CC33A-HCA3A
   11     5     7     9     9       0.000000     0.836800            3
     ; CC33A-CC31A-CC33A-HCA3A
   11     5     7    10     9       0.000000     0.836800            3
     ; CC33A-CC31A-CC33A-HCA3A
    1     5    11    12     9       0.000000     0.836800            3
     ; CC33A-CC31A-CC33A-HCA3A
    1     5    11    13     9       0.000000     0.836800            3
     ; CC33A-CC31A-CC33A-HCA3A
    1     5    11    14     9       0.000000     0.836800            3
     ; CC33A-CC31A-CC33A-HCA3A
    6     5    11    12     9       0.000000     0.836800            3
     ; HCA1A-CC31A-CC33A-HCA3A
    6     5    11    13     9       0.000000     0.836800            3
     ; HCA1A-CC31A-CC33A-HCA3A
    6     5    11    14     9       0.000000     0.836800            3
     ; HCA1A-CC31A-CC33A-HCA3A
    7     5    11    12     9       0.000000     0.836800            3
     ; CC33A-CC31A-CC33A-HCA3A
    7     5    11    13     9       0.000000     0.836800            3
     ; CC33A-CC31A-CC33A-HCA3A
    7     5    11    14     9       0.000000     0.836800            3
     ; CC33A-CC31A-CC33A-HCA3A


1. In [pairs] section I've kept it empty and made gen-pairs yes at
[defaults] section does it generates the value automatically? If yes,
is that a safe way to do it or fill up the parameters by myself?

2. Please see those parameters I've chosen and point out the errors if
I've made. I don't know if some more sections are to be added here.

Thank you very much.


>At minimum, some all-atom force field, because whatever you were doing before
>has no relationship to GROMOS and is unlikely to succeed.

>Isobutane is just the valine side chain, so that's certainly a model compound in
>existing force fields and should have parameters published and validated for any
>of the major all-atom force fields.  I know it's in CHARMM, and certainly others.

>Justin


On Fri, May 19, 2017 at 6:07 PM, Sailesh Bataju <thelaven at gmail.com> wrote:

> Hi Sir,
>
> You mean like choosing OPLS forcefield for all-atom model would be moer
> appropriate for me?
>
> Thank you.
>
> On Fri, May 19, 2017 at 5:15 PM, Sailesh Bataju <thelaven at gmail.com>
> wrote:
>
>> Hi Sir/Ma'am,
>>
>> I've finally created parameter file of isobutane using gromos54a7
>> forcefield for all-atom model. Some of the parameters for bond angle
>> parameters like H-C-H and C-C-H bond angle were not found in ffbonded.itp
>> file in the relevant forcefield, instead I used FTFE  -  CTFE  -  FTFE and
>> CLChl  - CChl  - CLChl respectively which i found it in the sample of the
>> file generated by https://atb.uq.edu.au/ website. Somehow luckily found
>> corresponding bond angle approximately equivalent to the experimental data
>> observed but didn't find the bond angle constant in experimental data.
>> Therefore I'm not sure if I can trust the parameter selected.
>>
>> I need your advice to help me decide to go further.
>> Thank you very much.
>>
>> --
>> Self-reliant is the great potential for success.
>>
>
>
>
> --
> Self-reliant is the great potential for success.
>



-- 
Self-reliant is the great potential for success.


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