Syntax:
temperature ID group-ID style args keyword value ...
full args = none partial args = x y z x,y,z = 0 or 1 ramp args = vdim vlo vhi dim clo chi vdim = vx or vy or vz vlo,vhi = subtract velocities between vlo and vhi (velocity units) dim = x or y or z clo,chi = lower and upper bound of domain to subtract from (distance units) region args = region-ID
units value = lattice or box
Examples:
temperature mine peptide full temperature new flow partial 1 1 0 temperature 2 all region border temperature 2nd middle ramp vx 0 8 y 2 12 units lattice
Description:
Define a method for computing the temperature of a group of atoms.
The ID of the temperature can be referred to in other commands which perform or modify temperature computations: thermo_modify, velocity, fix_modify, temp_modify.
The style determines how the temperature is computed. The full style means KE = dim/2 N k T, where KE = total kinetic energy of the group of atoms (sum of 1/2 m v^2), dim = 2 or 3 = dimensionality of the simulation, N = number of atoms in the group, k = Boltzmann constant, and T = temperature.
The partial style uses the same formula as full, except entire dimensions can be eliminated from the kinetic energy computation. This can be useful for systems where atoms are flowing, and only the thermal temperature in the non-flow directions is desired. A "0" means do not use the component of velocity in that dimension when computing KE. In the example above with arguments 1 1 0, only x and y velocities (not z) would be used in computing KE and temperature.
The ramp style can be used to eliminate an imposed velocity on a system before computing thermal KE. The meaning of these arguments is the same as for the velocity command which was presumably used to impose the velocity.
The region style will compute the temperature of the atoms that are both in the group and in the region volume of the specified region ID. This is useful for thermostatting on a varying set of atoms that fall within a geometric region of the simulation domain, where those atoms can change from one timestep to the next.
The units keyword determines the meaning of the distance units used for coordinates (c1,c2) and velocities (vlo,vhi) defined for the ramp style. A box value selects standard distance units as defined by the units command, e.g. Angstroms for units = real or metal. A lattice value means the distance units are in cubic lattice spacings; e.g. lattice spacings / tau. The lattice command must first be used to define a lattice.
A temperature with ID = default is pre-defined by LAMMPS and uses to a full style computation on the all group of atoms. All operations in LAMMPS that compute temperatures use the default ID unless the input script changes it.
Restrictions: none
Related commands:
thermo_modify, velocity, fix_modify, temp_modify
Default:
A temperature with ID = default is defined by LAMMPS, as if it had been specified as "temperature default all full". The option default is units = lattice.