amber03 HIP charges are wrong
As reported on the AMBER mailing list by David Case, "FWIW: the only other change I see is a change to the HIP charges in Nov.
2005--logs are unclear about why this change was made. As Carlos suggested, you might want to try to contact Yong Duan directly."
http://ffamber.cnsm.csulb.edu/ffamber.php reports the GROMACS validations were done with AMBER 8.0, which was released in 2004, so will not have this change.