dihedral problem

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1

Dear all,

I am trying to simulation long chain hydrocarbons in zeolite. I have generated the initial configuration using towhee cbmc. Now I am having few queries as listed below.

(1) After running for few steps(in lammps) it says Dihedral Problem. What could be the solution to this?

(2) When I lower the time step the simulation runs smoothly. How can it be related to the Dihedral Problem?

(3) The configuration generated by towhee has few of the long chain hydrocarbon atoms out of the simulation box. Can this be problematic? Most of the atoms of the long chain hydrocarbons are inside the simulation box and hence the com is inside the simulation box. I think this way the configuration should be all right.

Any comments or suggestions will be highly appreciated. Thanks in advance.

Kind regards
Bhaskar

2

See the Section_errors.html page of the manual. A Dihedral Problem
means a very bad configuration, which if it is occurring a few setps
in, likely mean your starting config is bad, or your force field
assignments are bad. Or you could be using too large a timestep.
Fix your input and the problem should go away.

The atoms being out of the box initially are not a problem. LAMMPS
will wrap them back inside.

Steve