[gmx-developers] multiplicity check on proper dihedral

[Tim Sirk]

Hello,

I've been using 3.3.3, and after updating to 4.0 RC4 I found that grompp doesn't
accept a proper dihedral with a multiplicity of zero. grompp returns this error:

Value of 'multiplicity' in Proper Dih. is 0, which is smaller than the minimum
of 1

I understand that mult=0 probably isn't expected, but it is part of a forcefield
(see below) that I've used with 3.3.3 and I'd like to continue using it. Might a
warning be sufficient, instead of a fatal error? Any input on a workaround would
be appreciated.

; CH1-CH1-CH2-CH2  =>  C22-C23-C24=C25
    25   24    23    22     1  0.000       7.47     1
    25   24    23    22     1  0.000       3.9      2
    25   24    23    22     1  180.000     1.1      3
    25   24    23    22     1  0.000      -2.8425   0
; CH1-CH1-CH2-CH2  =>  C24=C25-C26-C27
    27   26    25    24     1  0.000       7.47     1
    27   26    25    24     1  0.000       3.9      2
    27   26    25    24     1  180.000     1.1      3
    27   26    25    24     1  0.000      -2.8425   0


Thanks.

Tim Sirk
12C Randolph Hall
Graduate Research Assistant
Mechanical Engineering Dept
Virginia Tech