Syntax:
atom_style disk
atom_style hybrid disk additional_style
Examples:
atom_style disk atom_style hybrid disk disk/waves atom_style hybrid disk bond/gran/disk atom_style hybrid disk disk/waves bond/gran/disk
Description:
These atom styles are part of the USER-SEAICE package; they are only enabled if LIGGGHTS was built with that package.
They define the style of atoms to use in a sea ice simulation. The general rules for the usage of these atom styles are the same as for other styles, see the description of the atom_style command.
The basic atom style for sea ice simulations, without bonds and quasi-3D surface-waves effects, is disk. For simulations with surface waves, the additional style disk/waves is required. Simulations with bonds require the additional style bond/gran/disk. All granular styles store atom IDs and types, coordinates, velocities, diameter, mass and angular velocity (i.e., the set of attributes of the sphere style). These are the additional attributes of each disk-style:
| disk | thickness |
| bond/gran/disk | bonds |
| disk/waves | tilt |
In order to use the read_data command with these atom styles, each line in the Atoms section in the input file has to contain the following variables:
For atom_style disk: 8 columns (atom ID, type, diameter, thickness, density, 3 spatial coordinates).
For atom_style hybrid disk bond/gran/disk: 9 columns (atom ID, type, 3 spatial coordinates, diameter, thickness, density, molecule ID).
The molecule ID is meaningless in the context of granular systems, but is used for consistency of the read_data command with other bond styles. The disk/waves sub-style does not require any additional data to be read from file, i.e., the Atoms section contains the same columns as with atom_style disk.
If the bond/gran/disk is part of the hybrid style used, the following settings are required and/or strongly recommended:
newton off off communicate single cutoff value vel yes
Due to the first setting, forces due to pairwise and bonded interactions between atoms belonging to different processors are calculated by each processor separately, instead of being communicated between processors; see newton command for details. As a result of the second command, velocities, necessary to calculate pairwise interactions, are stored by ghosts atoms; see communicate command for details. For simulations with bonds, the value of the ghost cutoff distance value should be larger than the longest bond in the system, so that the bond information is correctly passed between processors. Finally, if very wide particle size distributions are used, it is necessary to set the one option of the neigh_modify command to a sufficiently high value, higher than the expected maximum number of neighbors a single atom can have.
Related commands:
read_data, pair_style, bond_style, fix_nve/disk
Default:
atom_style atomic
(Herman) Agnieszka Herman, Geosci. Model Devel., submitted (2015).