"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c :link(lws,http://lammps.sandia.gov) :link(ld,Manual.html) :link(lc,Section_commands.html#comm) :line fix nvt/sphere command :h3 fix nvt/sphere/omp command :h3 [Syntax:] fix ID group-ID nvt/sphere keyword value ... :pre ID, group-ID are documented in "fix"_fix.html command nvt/sphere = style name of this fix command additional thermostat related keyword/value pairs from the "fix nvt"_fix_nh.html command can be appended :ul [Examples:] fix 1 all nvt/sphere temp 300.0 300.0 100.0 fix 1 all nvt/sphere temp 300.0 300.0 100.0 drag 0.2 :pre [Description:] Perform constant NVT integration to update position, velocity, and angular velocity each timestep for finite-size spherical particles in the group using a Nose/Hoover temperature thermostat. V is volume; T is temperature. This creates a system trajectory consistent with the canonical ensemble. This fix differs from the "fix nvt"_fix_nh.html command, which assumes point particles and only updates their position and velocity. The thermostat is applied to both the translational and rotational degrees of freedom for the spherical particles, assuming a compute is used which calculates a temperature that includes the rotational degrees of freedom (see below). The translational degrees of freedom can also have a bias velocity removed from them before thermostatting takes place; see the description below. Additional parameters affecting the thermostat are specified by keywords and values documented with the "fix nvt"_fix_nh.html command. See, for example, discussion of the {temp} and {drag} keywords. This fix computes a temperature each timestep. To do this, the fix creates its own compute of style "temp/sphere", as if this command had been issued: compute fix-ID_temp group-ID temp/sphere :pre See the "compute temp/sphere"_compute_temp_sphere.html command for details. Note that the ID of the new compute is the fix-ID + underscore + "temp", and the group for the new compute is the same as the fix group. Note that this is NOT the compute used by thermodynamic output (see the "thermo_style"_thermo_style.html command) with ID = {thermo_temp}. This means you can change the attributes of this fix's temperature (e.g. its degrees-of-freedom) via the "compute_modify"_compute_modify.html command or print this temperature during thermodynamic output via the "thermo_style custom"_thermo_style.html command using the appropriate compute-ID. It also means that changing attributes of {thermo_temp} will have no effect on this fix. Like other fixes that perform thermostatting, this fix can be used with "compute commands"_compute.html that calculate a temperature after removing a "bias" from the atom velocities. E.g. removing the center-of-mass velocity from a group of atoms or only calculating temperature on the x-component of velocity or only calculating temperature for atoms in a geometric region. This is not done by default, but only if the "fix_modify"_fix_modify.html command is used to assign a temperature compute to this fix that includes such a bias term. See the doc pages for individual "compute commands"_compute.html to determine which ones include a bias. In this case, the thermostat works in the following manner: the current temperature is calculated taking the bias into account, bias is removed from each atom, thermostatting is performed on the remaining thermal degrees of freedom, and the bias is added back in. :line Styles with a {gpu}, {intel}, {kk}, {omp}, or {opt} suffix are functionally the same as the corresponding style without the suffix. They have been optimized to run faster, depending on your available hardware, as discussed in "Section_accelerate"_Section_accelerate.html of the manual. The accelerated styles take the same arguments and should produce the same results, except for round-off and precision issues. These accelerated styles are part of the GPU, USER-INTEL, KOKKOS, USER-OMP and OPT packages, respectively. They are only enabled if LAMMPS was built with those packages. See the "Making LAMMPS"_Section_start.html#start_3 section for more info. You can specify the accelerated styles explicitly in your input script by including their suffix, or you can use the "-suffix command-line switch"_Section_start.html#start_7 when you invoke LAMMPS, or you can use the "suffix"_suffix.html command in your input script. See "Section_accelerate"_Section_accelerate.html of the manual for more instructions on how to use the accelerated styles effectively. [Restart, fix_modify, output, run start/stop, minimize info:] This fix writes the state of the Nose/Hoover thermostat to "binary restart files"_restart.html. See the "read_restart"_read_restart.html command for info on how to re-specify a fix in an input script that reads a restart file, so that the operation of the fix continues in an uninterrupted fashion. The "fix_modify"_fix_modify.html {temp} option is supported by this fix. You can use it to assign a "compute"_compute.html you have defined to this fix which will be used in its thermostatting procedure. The "fix_modify"_fix_modify.html {energy} option is supported by this fix to add the energy change induced by Nose/Hoover thermostatting to the system's potential energy as part of "thermodynamic output"_thermo_style.html. This fix computes the same global scalar and global vector of quantities as does the "fix nvt"_fix_nh.html command. This fix can ramp its target temperature over multiple runs, using the {start} and {stop} keywords of the "run"_run.html command. See the "run"_run.html command for details of how to do this. This fix is not invoked during "energy minimization"_minimize.html. [Restrictions:] This fix requires that atoms store torque and angular velocity (omega) and a radius as defined by the "atom_style sphere"_atom_style.html command. All particles in the group must be finite-size spheres. They cannot be point particles. [Related commands:] "fix nvt"_fix_nh.html, "fix nve_sphere"_fix_nve_sphere.html, "fix nvt_asphere"_fix_nvt_asphere.html, "fix npt_sphere"_fix_npt_sphere.html, "fix_modify"_fix_modify.html [Default:] none