[lammps-users] Heat capacity of water

Dear Farrokh,

As Xiaopeng said, you should take care of unit conversion.
If you divide 108 kCal/mole-K to 6.022e23 then you will have 1.793e-22 kCal/K. Since your system have 7000 water molecules, so your system have 2.092e-16 gram water. Then the specific heat will be around 0.86 kCal/gram-K which is not so far from the specific heat of water (1 kCal/gram-K) at 300 K.

Best regards,
Ali Rajabpour