[gmx-users] Problems with ion names in OPLS and gromacs 4.0.2

[DimitryASuplatov]

Hello,
I want neutralize negative charge in my structure. I use genion to add
80 Na and 71 Cl. Than I edit top file manually to decrease SOL number by
151 and add two lines for ions. Since I use OPLSAA they should look like
this (considering names in gromacs/share/gromacs/top/ions.itp)

NA+             80
CL-             71

When I run grompp afterwards I receive this message:

--------------------------------------------------------
Warning: atom name 105260 in 1klc_final_frc.top and
1klc_final_frc.si.gro does not match (NA - Na)
Warning: atom name 105261 in 1klc_final_frc.top and
1klc_final_frc.si.gro does not match (NA - Na)
(more than 20 non-matching atom names)

WARNING 1 [file 1klc_final_frc.top, line 42]:
  151 non-matching atom names
  atom names from 1klc_final_frc.top will be used
  atom names from 1klc_final_frc.si.gro will be ignored
--------------------------------------------------------

That was expected since gro file identifies the ions as "Na" and "Cl",
but this is the first time in my experience when grompp throws out this:
-------------------------------------------------------
Program grompp, VERSION 4.0.2
Source code file: gmx_fatal.c, line: 481

Fatal error:
Too many warnings (1), grompp terminated.
If you are sure all warnings are harmless, use the -maxwarn option.
-------------------------------------------------------


Is this a problem or should I simply set -maxwarn to 2?

Thanks. I appreciate your time.
SDA