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read_particles command


read_particles file Nstep 


read_particles dump.sphere 10500 


Read a snapshot of particles from a previously created dump file and add them to the simulation domain. This is a means of reading in particles from a previous SPARTA simulation or created as output by another code. The create_particles, fix emit/face, and read_restart commands are alternate ways to generate particles for a simulation.

The dump file must be in the SPARTA format created by the dump particles command which is described on its doc page.

Currently, each line of particle data in the file must have 8 fields in the following order. At some point we may generalize this format.

id, type, x, y, z, vx, vy, vz 

The id is any positive integer, which can simply be set to values from 1 to Nparticles if desired. The type is the species ID from 1 to Nspecies. The value corresponds to the order in which species are defined in the current input script via the species command. The x,y,z values are the particle coordinates which must be inside (or on the surface of) the simulation box. If a particle is outside the box it will be skipped when the file is read. For 2d or axisymmetric simulations z = 0.0 should be used, though SPARTA does not check for this. The vx,vy,vz values are the particle velocity. The rotational and vibrational energies for the new particles are set to 0.0.

When the reading of particles is complete, the number of particles read is printed to the screen. If the number is smaller than the particles in the file, it is because some were outside the simulation box.

A check is made for any particle inside a surface object which triggers an error. However the check is only for grid cells entirely inside a surface object. Particles in grid cells which are cut by surfaces are not checked. It is your responsibility to insure particles close to surfaces are actually outside the surface object. If this is not the case, errors may be triggered once particles begin to move.

Restrictions: none

Related commands:

create_particles, fix emit/face

Default: none