# thermo_modify command

## Syntax

    thermo_modify keyword value ...

- one or more keyword/value pairs may be listed
- keyword = lost or norm or flush or line or format

    lost value = error or warn or ignore
    norm value = yes or no
    flush value = yes or no
    line value = one or multi
    format values = int string or float string or M string
      M = integer from 1 to N, where N = # of quantities being printed
      string = C-style format string

## Examples

    thermo_modify lost ignore flush yes
    thermo_modify line multi format float %g

## Description

Set options for how thermodynamic information is computed and printed by LIGGGHTS(R)-PUBLIC.

Warning

These options apply to the currently defined thermo style. When you specify a thermo_style command, all thermodynamic settings are restored to their default values, including those previously reset by a thermo_modify command. Thus if your input script specifies a thermo_style command, you should use the thermo_modify command after it.

The lost keyword determines whether LIGGGHTS(R)-PUBLIC checks for lost atoms each time it computes thermodynamics and what it does if atoms are lost. An atom can be “lost” if it moves across a non-periodic simulation box boundary or if it moves more than a box length outside the simulation domain (or more than a processor sub-domain length) before reneighboring occurs. The latter case is typically due to bad dynamics, e.g. too large a timestep or huge forces and velocities. If the value is ignore, LIGGGHTS(R)-PUBLIC does not check for lost atoms. If the value is error or warn, LIGGGHTS(R)-PUBLIC checks and either issues an error or warning. The code will exit with an error and continue with a warning. A warning will only be issued once, the first time an atom is lost. This can be a useful debugging option.

Warning

For compuatational efficiency, this lost check is just a simple check if the total number of atoms in the system decreases. So for simulations where particles are continuously inserted, “lost” atoms might not be detected.

The norm keyword determines whether various thermodynamic output values are normalized by the number of atoms or not, depending on whether it is set to yes or no. Different unit styles have different defaults for this setting (see below). Even if norm is set to yes, a value is only normalized if it is an “extensive” quantity, meaning that it scales with the number of atoms in the system. For the thermo keywords described by the doc page for the thermo_style command, all energy-related keywords are extensive. Other keywords such are “intensive” meaning their value is independent (in a statistical sense) of the number of atoms in the system and thus are never normalized. For thermodynamic output values extracted from fixes and computes in a thermo_style custom command, the doc page for the individual fix or compute lists whether the value is “extensive” or “intensive” and thus whether it is normalized. Thermodynamic output values calculated by a variable formula are assumed to be “intensive” and thus are never normalized. You can always include a divide by the number of atoms in the variable formula if this is not the case.

The flush keyword invokes a flush operation after thermodynamic info is written to the log file. This insures the output in that file is current (no buffering by the OS), even if LIGGGHTS(R)-PUBLIC halts before the simulation completes.

The line keyword determines whether thermodynamics will be printed as a series of numeric values on one line or in a multi-line format with 3 quantities with text strings per line and a dashed-line header containing the timestep and CPU time. This modify option overrides the one and multi thermo_style settings.

The format keyword sets the numeric format of individual printed quantities. The int and float keywords set the format for all integer or floating-point quantities printed. The setting with a numeric value M (e.g. format 5 %10.4g) sets the format of the Mth value printed in each output line, e.g. the 5th column of output in this case. If the format for a specific column has been set, it will take precedent over the int or float setting.

Warning

The thermo output values step and atoms are stored internally as 8-byte signed integers, rather than the usual 4-byte signed integers. When specifying the “format int” keyword you can use a “%d”-style format identifier in the format string and LIGGGHTS(R)-PUBLIC will convert this to the corresponding “%lu” form when it is applied to those keywords. However, when specifying the “format M string” keyword for step and natoms, you should specify a string appropriate for an 8-byte signed integer, e.g. one with “%ld”.

## Restrictions

> none

## Related commands

thermo, thermo_style

## Default

The option defaults are lost = ignore, norm = yes for unit style of lj, norm = no for unit style of real and metal, flush = no.

The defaults for the line and format options depend on the thermo style. For styles “one” and “custom”, the line and format defaults are “one”, “%8d”, and “%12.8g”. For style “multi”, the line and format defaults are “multi”, “%8d”, and “%14.4f”.