# fix nve/asphere/noforce command

## Syntax

fix ID group-ID nve/asphere/noforce

• ID, group-ID are documented in fix command
• nve/asphere/noforce = style name of this fix command

## Examples

fix 1 all nve/asphere/noforce

## Description

Perform updates of position and orientation, but not velocity or angular momentum for atoms in the group each timestep. In other words, the force and torque on the atoms is ignored and their velocity and angular momentum are not updated. The atom velocities and angular momenta are used to update their positions and orientation.

This is useful as an implicit time integrator for Fast Lubrication Dynamics, since the velocity and angular momentum are updated by the pair_style lubricuteU command.

Restart, fix_modify, output, run start/stop, minimize info:

No information about this fix is written to binary restart files. None of the fix_modify options are relevant to this fix. No global or per-atom quantities are stored by this fix for access by various output commands. No parameter of this fix can be used with the start/stop keywords of the run command. This fix is not invoked during energy minimization.

## Restrictions

This fix is part of the ASPHERE package. It is only enabled if LAMMPS was built with that package. See the Build package doc page for more info.

This fix requires that atoms store torque and angular momentum and a quaternion as defined by the atom_style ellipsoid command.

All particles in the group must be finite-size. They cannot be point particles, but they can be aspherical or spherical as defined by their shape attribute.