Syntax:
thermo_style style args
one args = none
multi args = none
custom args = list of attributes
possible attributes = step, elapsed, elaplong, dt, cpu, tpcpu, spcpu,
atoms, temp, press, pe, ke, etotal, enthalpy,
evdwl, ecoul, epair, ebond, eangle, edihed, eimp,
emol, elong, etail,
vol, lx, ly, lz, xlo, xhi, ylo, yhi, zlo, zhi,
xy, xz, yz, xlat, ylat, zlat,
pxx, pyy, pzz, pxy, pxz, pyz,
fmax, fnorm,
cella, cellb, cellc, cellalpha, cellbeta, cellgamma,
c_ID, c_ID[I], c_ID[I][J],
f_ID, f_ID[I], f_ID[I][J],
v_name
step = timestep
elapsed = timesteps since start of this run
elaplong = timesteps since start of initial run in a series of runs
dt = timestep size
cpu = elapsed CPU time in seconds
tpcpu = time per CPU second
spcpu = timesteps per CPU second
atoms = # of atoms
temp = temperature
press = pressure
pe = total potential energy
ke = kinetic energy
etotal = total energy (pe + ke)
enthalpy = enthalpy (etotal + press*vol)
evdwl = VanderWaal pairwise energy
ecoul = Coulombic pairwise energy
epair = pairwise energy (evdwl + ecoul + elong + etail)
ebond = bond energy
eangle = angle energy
edihed = dihedral energy
eimp = improper energy
emol = molecular energy (ebond + eangle + edihed + eimp)
elong = long-range kspace energy
etail = VanderWaal energy long-range tail correction
vol = volume
lx,ly,lz = box lengths in x,y,z
xlo,xhi,ylo,yhi,zlo,zhi = box boundaries
xy,xz,yz = box tilt for triclinic (non-orthogonal) simulation boxes
xlat,ylat,zlat = lattice spacings as calculated by lattice command
pxx,pyy,pzz,pxy,pxz,pyz = 6 components of pressure tensor
fmax = max component of force on any atom in any dimension
fnorm = length of force vector for all atoms
cella,cellb,cellc = periodic cell lattice constants a,b,c
cellalpha, cellbeta, cellgamma = periodic cell angles alpha,beta,gamma
c_ID = global scalar value calculated by a compute with ID
c_ID[I] = Ith component of global vector calculated by a compute with ID
c_ID[I][J] = I,J component of global array calculated by a compute with ID
f_ID = global scalar value calculated by a fix with ID
f_ID[I] = Ith component of global vector calculated by a fix with ID
f_ID[I][J] = I,J component of global array calculated by a fix with ID
v_name = scalar value calculated by an equal-style variable with name
Examples:
thermo_style multi thermo_style custom step temp pe etotal press vol thermo_style custom step temp etotal c_myTemp v_abc
Description:
Set the style and content for printing thermodynamic data to the screen and log file.
Style one prints a one-line summary of thermodynamic info that is the equivalent of "thermo_style custom step temp epair emol etotal press". The line contains only numeric values.
Style multi prints a multiple-line listing of thermodynamic info that is the equivalent of "thermo_style custom etotal ke temp pe ebond eangle edihed eimp evdwl ecoul elong press". The listing contains numeric values and a string ID for each quantity.
Style custom is the most general setting and allows you to specify which of the keywords listed above you want printed on each thermodynamic timestep. Note that the keywords c_ID, f_ID, v_name are references to computes, fixes, and equal-style variables that have been defined elsewhere in the input script or can even be new styles which users have added to LAMMPS (see the Section_modify section of the documentation). Thus the custom style provides a flexible means of outputting essentially any desired quantity as a simulation proceeds.
All styles except custom have vol appended to their list of outputs if the simulation box volume changes during the simulation.
The values printed by the various keywords are instantaneous values, calculated on the current timestep. Time-averaged quantities, which include values from previous timesteps, can be output by using the f_ID keyword and accessing a fix that does time-averaging such as the fix ave/time command.
Options invoked by the thermo_modify command can be used to set the one- or multi-line format of the print-out, the normalization of thermodynamic output (total values versus per-atom values for extensive quantities (ones which scale with the number of atoms in the system), and the numeric precision of each printed value.
IMPORTANT NOTE: When you use a "thermo_style" command, all thermodynamic settings are restored to their default values, including those previously set by a thermo_modify command. Thus if your input script specifies a thermo_style command, you should use the thermo_modify command after it.
Several of the thermodynamic quantities require a temperature to be computed: "temp", "press", "ke", "etotal", "enthalpy", "pxx", etc. By default this is done by using a temperature compute which is created when LAMMPS starts up, as if this command had been issued:
compute thermo_temp all temp
See the compute temp command for details. Note that the ID of this compute is thermo_temp and the group is all. You can change the attributes of this temperature (e.g. its degrees-of-freedom) via the compute_modify command. Alternatively, you can directly assign a new compute (that calculates temperature) which you have defined, to be used for calculating any thermodynamic quantity that requires a temperature. This is done via the thermo_modify command.
Several of the thermodynamic quantities require a pressure to be computed: "press", "enthalpy", "pxx", etc. By default this is done by using a pressure compute which is created when LAMMPS starts up, as if this command had been issued:
compute thermo_press all pressure thermo_temp
See the compute pressure command for details. Note that the ID of this compute is thermo_press and the group is all. You can change the attributes of this pressure via the compute_modify command. Alternatively, you can directly assign a new compute (that calculates pressure) which you have defined, to be used for calculating any thermodynamic quantity that requires a pressure. This is done via the thermo_modify command.
Several of the thermodynamic quantities require a potential energy to be computed: "pe", "etotal", "ebond", etc. This is done by using a pe compute which is created when LAMMPS starts up, as if this command had been issued:
compute thermo_pe all pe
See the compute pe command for details. Note that the ID of this compute is thermo_pe and the group is all. You can change the attributes of this potential energy via the compute_modify command.
The kinetic energy of the system ke is inferred from the temperature of the system with 1/2 Kb T of energy for each degree of freedom. Thus, using different compute commands for calculating temperature, via the thermo_modify temp command, may yield different kinetic energies, since different computes that calculate temperature can subtract out different non-thermal components of velocity and/or include different degrees of freedom (translational, rotational, etc).
The potential energy of the system pe will include contributions from fixes if the fix_modify thermo option is set for a fix that calculates such a contribution. For example, the fix wall/lj93 fix calculates the energy of atoms interacting with the wall. See the doc pages for "individual fixes" to see which ones contribute.
A long-range tail correction etail for the VanderWaal pairwise energy will be non-zero only if the pair_modify tail option is turned on. The etail contribution is included in evdwl, pe, and etotal, and the corresponding tail correction to the pressure is included in press and pxx, pyy, etc.
The step, elapsed, and elaplong keywords refer to timestep count. Step is the current timestep, or iteration count when a minimization is being performed. Elapsed is the number of timesteps elapsed since the beginning of this run. Elaplong is the number of timesteps elapsed since the beginning of an initial run in a series of runs. See the start and stop keywords for the run for info on how to invoke a series of runs that keep track of an initial starting time. If these keywords are not used, then elapsed and elaplong are the same value.
The cpu keyword is elapsed CPU seconds since the beginning of this run. The tpcpu and spcpu keywords are measures of how fast your simulation is currently running. The tpcpu keyword is simulation time per CPU second, where simulation time is in time units. E.g. for metal units, the tpcpu value would be picoseconds per CPU second. The spcpu keyword is the number of timesteps per CPU second. Both quantities are on-the-fly metrics, measured relative to the last time they were invoked. Thus if you are printing out thermodyamic output every 100 timesteps, the two keywords will continually output the time and timestep rate for the last 100 steps. The tpcpu keyword does not attempt to track any changes in timestep size, e.g. due to using the fix dt/reset command.
The fmax and fnorm keywords are useful for monitoring the progress of an energy minimization. The fmax keyword calculates the maximum force in any dimension on any atom in the system, or the infinity-norm of the force vector for the system. The fnorm keyword calculates the 2-norm or length of the force vector.
The keywords cella, cellb, cellc, cellalpha, cellbeta, cellgamma, correspond to the usual crystallographic quantities that define the periodic unit cell of a crystal. See this section of the doc pages for a geometric description of triclinic periodic cells, including a precise defintion of these quantities in terms of the internal LAMMPS cell dimensions lx, ly, lz, yz, xz, xy,
The c_ID and c_ID[I] and c_ID[I][J] keywords allow global values calculated by a compute to be output. As discussed on the compute doc page, computes can calculate global, per-atom, or local values. Only global values can be referenced by this command. However, per-atom compute values can be referenced in a variable and the variable referenced by thermo_style custom, as discussed below.
The ID in the keyword should be replaced by the actual ID of a compute that has been defined elsewhere in the input script. See the compute command for details. If the compute calculates a global scalar, vector, or array, then the keyword formats with 0, 1, or 2 brackets will reference a scalar value from the compute.
Note that some computes calculate "intensive" global quantities like temperature; others calculate "extensive" global quantities like kinetic energy that are summed over all atoms in the compute group. Intensive quantities are printed directly without normalization by thermo_style custom. Extensive quantities may be normalized by the total number of atoms in the simulation (NOT the number of atoms in the compute group) when output, depending on the thermo_modify norm option being used.
The f_ID and f_ID[I] and f_ID[I][J] keywords allow global values calculated by a fix to be output. As discussed on the fix doc page, fixes can calculate global, per-atom, or local values. Only global values can be referenced by this command. However, per-atom fix values can be referenced in a variable and the variable referenced by thermo_style custom, as discussed below.
The ID in the keyword should be replaced by the actual ID of a fix that has been defined elsewhere in the input script. See the fix command for details. If the fix calculates a global scalar, vector, or array, then the keyword formats with 0, 1, or 2 brackets will reference a scalar value from the fix.
Note that some fixes calculate "intensive" global quantities like timestep size; others calculate "extensive" global quantities like energy that are summed over all atoms in the fix group. Intensive quantities are printed directly without normalization by thermo_style custom. Extensive quantities may be normalized by the total number of atoms in the simulation (NOT the number of atoms in the fix group) when output, depending on the thermo_modify norm option being used.
The v_name keyword allow the current value of a variable to be output. The name in the keyword should be replaced by the variable name that has been defined elsewhere in the input script. Only equal-style variables can be referenced. See the variable command for details. Variables of style equal can reference per-atom properties or thermodynamic keywords, or they can invoke other computes, fixes, or variables when evaluated, so this is a very general means of creating thermodynamic output.
See Section_modify for information on how to add new compute and fix styles to LAMMPS to calculate quantities that can then be referenced with these keywords to generate thermodynamic output.
Restrictions:
This command must come after the simulation box is defined by a read_data, read_restart, or create_box command.
Related commands:
thermo, thermo_modify, fix_modify, compute temp, compute pressure
Default:
thermo_style one