Constraining NEB Calculations to only one Degree of Freedom

LAMMPS LAMMPS General Discussion
1

Hello everyone,

in this Publication (http://dx.doi.org/10.1088/0965-0393/20/3/035019), NEB Calculations are carried out, where only the Z-Coordinate of the NEB-Atoms is controlled by the NEB Calculations, whereas the X and Y Coordinate of the neb-atoms (as well as the (X,Y,Z) - Coordinates of the Non-NEB Atoms) are controlled by the conventional minimizer.

At least according to the lammps documentation, there is no possibility described, to achieve this behaviour. My attempt of using fix ${fix-id} neb-atoms setforce 0.0 0.0 NULL lead to no movement in x & y direction of the neb-atoms during the NEB-Calculations.

So is there a way to achieve the described behaviour of limiting the NEB to single Degrees of Freedom (and not to atoms only) in Lammps implemented currently?

Warm Regards
Benedikt

2

There are no undocumented features in LAMMPS. We require documentation for every feature added and refuse inclusion if that condition is not met. Thus any feature you would want to use that is not documented will have to be implemented in C++ first.

3

I guess the most lightweight way is to adjust fix store/force so it can also invoked by damped dynamics minimizers, so that something like

fix sf all store/force
fix neb all neb ...
fix onlyxy all setforce f_sf[1] f_sf[2] NULL

will work.