# [lammps-users] outputs of stress units

For style real, these are the units:

mass = grams/mole
distance = Angstroms
time = femtoseconds
energy = Kcal/mole
velocity = Angstroms/femtosecond
force = Kcal/mole-Angstrom
temperature = degrees K
pressure = atmospheres
viscosity = Poise
charge = multiple of electron charge (+1.0 is a proton)
dipole = charge*Angstroms
electric field = volts/Angstrom

But I don��t know the mean of ��pressure = atmospheres��?

As far as I know, if real units used, units of per-atom stress by output from ��compute stress/atom command�� is in virial stress. It is also really a stress-volume formulation, meaning the computed quantity is in units of pressure-volume. It would need to be divided by a per-atom volume to have units of stress (pressure).
What is the units of the output virial stress in terms of (Angstrom, grams, femtosecons, etc.)?
Then I can get the real stress by divided by per-atom volume (Angstrom3).
Thank you.

Yang

Yang,

An atmosphere is equivalent to 101325 Pa.

Also, an atmosphere is also equivalent to 6.10193e-9 gm/(angsfsfs*mole).

Paul