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git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@1736 f3b2605a-c512-4ea7-a41b-209d697bcdaa

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sjplimp
2008-04-10 21:14:17 +00:00
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doc/units.html
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@ -30,15 +30,20 @@ and data file, as well as quantities output to the screen, log file,
and dump files. Typically, this command is used at the very beginning
of an input script.
</P>
<P>For real and metallic units, LAMMPS uses physical constants from
<P>For <I>real</I> and <I>metal</I> units, LAMMPS uses physical constants from
www.physics.nist.gov. For the definition of Kcal in real units, LAMMPS
uses the thermochemical calorie = 4.184 J.
</P>
<P>For style <I>lj</I>, all quantities are unitless. The formula relating the
reduced or unitless quantity (with an asterisk) to the same quantity
with units is also given:
<P>For style <I>lj</I>, all quantities are unitless. Without loss of
generality, LAMMPS sets the fundamental quantities mass, sigma,
epsilon, and the Boltzmann constant = 1. The masses, distances,
energies you specify are multiples of these fundamental values. The
formulas relating the reduced or unitless quantity (with an asterisk)
to the same quantity with units is also given. Thus you can use the
mass & sigma & epsilon values for a specific material and convert the
results from a unitless LJ simulation into physical quantities.
</P>
<UL><LI>m (mass) = epsilon = sigma = tau = Boltzmann constant = 1
<UL><LI>mass = mass or m
<LI>distance = sigma, where x* = x / sigma
<LI>time = tau, where tau = t* = t (Kb T / m / sigma^2)^1/2
<LI>energy = epsilon, where E* = E / epsilon
@ -53,8 +58,7 @@ with units is also given:
</UL>
<P>For style <I>real</I>, these are the units:
</P>
<UL><LI>Boltzmann constant = 0.0019872067 Kcal/mole per degree K
<LI>mass = grams/mole
<UL><LI>mass = grams/mole
<LI>distance = Angstroms
<LI>time = femtoseconds
<LI>energy = Kcal/mole
@ -69,8 +73,7 @@ with units is also given:
</UL>
<P>For style <I>metal</I>, these are the units:
</P>
<UL><LI>Boltzmann constant = 8.617343e-5 eV per degree K
<LI>mass = grams/mole
<UL><LI>mass = grams/mole
<LI>distance = Angstroms
<LI>time = picoseconds
<LI>energy = eV