Re: [gmx-users] acpype generated different tip3p water paramters

Hi Alan, So is acpype using a conversion factor of 4.184 for dihedral force constant? I found some dihedral constants as 0.156 in the amber format, which should be 0.156*4.184=0.652704 in gromacs unit. However, acpype gave a force constant of 0.65084 after conversion, which is slightly off. I

Re: [gmx-users] acpype generated different tip3p water paramters

Indeed, if you do the other way: 0.65084/4.184 = 0.1 ~ 0.156 Alan On 6 October 2011 08:17, Yun Shi yunsh...@gmail.com wrote: Hi Alan, So is acpype using a conversion factor of 4.184 for dihedral force constant? I found some dihedral constants as 0.156 in the amber format, which

Re: [gmx-users] acpype generated different tip3p water paramters

Hi Yun, ACPYPE is working fine. What happens here is I choose the reproduce the exact values one sees in AMBER. Now why GMX tip3p file choose a different value, I don't know. Nevertheless, it's pretty simple to put whatever value you want there if you think you need. Alan On 26 September 2011

[gmx-users] acpype generated different tip3p water paramters

Hi all, I just noted that the tip3p water converted from amber format to gromacs format is [ moleculetype ] ; molname nrexcl ; TIP3P model WAT 2 [ atoms ] ; nr type resnr residue atom cgnr charge mass 1 OW 1 WAT O 1 -0.834