[gmx-users] angle constraints

[Mark Abraham]

On 24/07/2012 3:21 PM, tarak karmakar wrote:
> Dear All,
>
>
> I am constraining one angle in my protein sample by incorporating " [
> constraints ]" block in topology file as
>
>
> [ constraints ]
> ;  index1  index2  index3   funct     angle
>   6064 6063 6065     1   180.0
>
> while doing that its showing the following error
>
> Program grompp, VERSION 4.5.5
> Source code file: topdirs.c, line: 174
>
> Fatal error:
> Invalid constraints type 6065
> For more information and tips for troubleshooting, please check the GROMACS
> website at http://www.gromacs.org/Documentation/Errors

As you will see in table 5.6, this is not a valid option for 
[constraints] - you can only specify bonds. You will need to construct a 
triangle of bond constraints.

Mark

>
>
> Then I rechecked the angle block, that specific angle is there in that
> angle section, part of it as follows
>   6039  6057  6058     1
>   6039  6057  6059     1
>   6058  6057  6059     1
>   6064  6063  6065     1
>   6067  6066  6068     1
>   6067  6066  6069     1
>   6068  6066  6069     1
>   6071  6070  6072     1
>   6071  6070  6073     1
>   6072  6070  6073     1
>
> [ constraints ]
> ;  index1  index2  index3   funct     angle
>   6064 6063 6065     1   180.0
>
> [ dihedrals ]
> ;  ai    aj    ak    al funct            c0            c1
> c2            c3            c4
>
>