# [lammps-users] units real

Dear Maosheng,

The number of moles used to calculate any per mol quantity is simply 1/N_A
Te conversion factor does not depend on the actual no. of atoms (moles) in the system.

Best,
Mario

Dear Mario，
Thank you for your letters. I know what you say. But when we calculate the kappa, we need know the heat flux. For the units：real, the thremal quantity: heat_swap, its units is Kcal/mol, for example, the heat_swap I get is:
#TimeStep f_heat_swap
200000 15545.4
300000 46405.2
400000 77496
500000 108924
600000 140580
for Total_Time_Elapsed 600000dt, heat_swap is 140580Kcal/mol=1405804186/6.02e23 J/atom.(Avogadro’s number=6.02e23 )
In the “Thermal conductivity= (heat flux/2/Total_Time_Elapsed)/ Temperature Slope/Cross Section”, I think the heat flux is different from heat_swap .Am I right?
Best
Maosheng

Dear Maosheng,

The units of heat_swap, after multiplication of conversion factors,
is J and not J/atom.

As described below, the total kinetic energy transferred by these swaps is computed by the fix and can be output. Dividing this quantity by time and the cross-sectional area of the simulation box yields a heat flux. The ratio of heat flux to the slope of the temperature profile is the thermal conductivity of the fluid, in appopriate units. See the Muller-Plathe paper for details.

Best,
Mario

2010/11/15 maosheng chai <[email protected]…24…>

Dear Mario，
Thank you for your response. That means the result I get multiply conversion factors (kCal2J = 4186.0/6.02214e23) is OK !
Best,
Maosheng