[gmx-users] Charge fitting

[parto haghighi]

Dear GMX usesr,

I have to do charge fitting for a small molecule like ethanol.
I have applied PRODRG to generate .gro and .itp for ethanol but it has
wrong atomic charge.
To correct it I have to use gromos 43a1 force field parameters to assign
charges on each atom (Is it right?)

I have red a paper ( Practical Considerations for Building
GROMOS-Compatible Small-Molecule Topologies
Justin A. Lemkul, William J. Allen, and David R. Bevan*) about this issue.
In this paper they assign these value to each atom:

H3C     0.000
CH2     0.150
O        -0.548
H         0.398

My question is:
In a gromos 43a1 force field and in .rtp file for CH3 in ALA and TMP:

[ ALA ]
 [ atoms ]
    N     N    -0.28000     0
    H     H     0.28000     0
  * CA   CH1     0.00000     1
   CB   CH3     0.00000     1*
    C     C       0.380     2
    O     O      -0.380     2

[ TMP ]
 [ atoms ]
   N1    NR    -0.36000     0
   C2     C     0.36000     0
  NA2    NT    -0.83000     1
.
.
.
* CM13   CH3     0.18000     6*
  C15     C     0.18000     7
  O15    OA    -0.36000     7
* CM15   CH3     0.18000     7*
  C14     C     0.18000     8
  O14    OA    -0.36000     8
* CM14   CH3     0.18000     8*

and for atom O I have same problem:

[ ADE ]
 [ atoms ]
    P     P     0.99000     0
  O1P    OM    -0.63500     0
  O2P    OM    -0.63500     0
 * O5*    OA    -0.36000     0*
  C5*   CH2     0.00000     1.
.
.

 * O2*    OA    -0.54800     8*
  H2*     H     0.39800     8
  C3*   CH1       0.000     9
 * O3*    OA      -0.360    10*

So I am confused which one of these charges must be considered as a correct
charge when I dont have a reference like mentioned paper?

Thanks in advance.
P.Haghighi
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