[gmx-users] rtp topology file for ligand

[amna khan]

hi all,

 i generated the .itp file for my ligand using ATB,
and i have generated the protein topology file by using the forcefield 13

my question is i need to generate the *ligand .top and .gro files*

and when i use the command


*pdb2gmx -f  lig.pdb -o igand.gro -i lig.itp -p iig.top

*
*the error arises that
Fatal error:
Residue 'LIG' not found in residue topology database


*
what should i do ?

how to create the rtp file for my ligand ... i have read the tutorail but i
am not getting it what steps* exactly should i do please please help me and
guide me in making the .rtp file for my ligand
*

regards
amna khan