[lammps-users] About boltz in file "force.h"

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1


In “force.h”,
double boltz; // Boltzmann constant (eng/degree-K)
I think the line should be changed to be:
double boltz; // Boltzmann constant (eng/temp)
because the unit of boltz is energy unit/temperature unit

Xiaoliang
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2

degree-K is temperature, i.e. the temperature in degrees Kelvin

Steve

3

I mean if the unit of boltz should be in some relation with units user defined, i.e., units lj, units metal ,etc. not just eng/degree-K

Maybe degree-K should be the temperature unit as in units command?

Am I wrong?

Xiaoliang

— 10年4月29日，周四, Steve Plimpton [email protected] 写道：

4

I dont see anything wrong, myself. The value of boltz is correctly defined in all units in Energy/K.

for metal, it is in eV/K
for si it is in J/K
for cts it is in ergs/K
for reduced, it is 1
for real, it is kCal/mol/K

5

Xiaoliang,

Technically, you are right, because the lj unit of temperature is arbitrary, and so is not necessarily Kelvin. Also, there may come a time when LAMMPS supports a temperature unit of Fahrenheit (unlikely) or maybe kilokelvin (why not!). That said, the existing description should be pretty unambiguous to most people smart enough to read the source code.

Aidan