[gmx-users] gromacs is not recognising opls ff

[Justin Lemkul]

On 8/26/19 7:04 AM, Ayesha Fatima wrote:
> Dear All,
> I have come across another issue
> When i want to use opls itp for cholesterol, it gives me this error " Fatal
> error:
> Residue 'OL' not found in residue topology database"
> It does not take CHOL as the residue name as given below

That suggests your input file has incorrect formatting. If it is a PDB 
file, the column positions are fixed. The error is consistent with the 
"CHOL" residue name having been shifted by two characters/columns.

-Justin

> [ atoms ]
> ;   nr       type  resnr residue  atom   cgnr     charge       mass  typeB
>     chargeB      massB
>          1  opls_158   1   CHOL      C1      1   0.2050      12.011
>          2  opls_140   1   CHOL      H1      1   0.0600      1.008
>          3  opls_154   1   CHOL      O1      1  -0.6830      15.9994
>
> Any suggestions?
> Thank you
> regards

-- 
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Justin A. Lemkul, Ph.D.
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