Specific heat question

[David Gunn]

Hi all - quick question regarding the specific heat; in the manual it states that the units are kB/spin, however I thought for specific heat capacities the units must be mass-related i.e. kg-1. Is someone able to comment on this? Also, just to confirm, if Vampire is calculating the isochoric heat capacity, the SI units should be JK-1kg-1?

Thanks!

David.

[gabo...@gmail.com]

I recall another user working on that at [1].

I don't know if they resolved it.  I also don't know if they did a dimensional analysis [2] on what they did or not.

From looking at [3], VAMPIRE should output a mean-specific-heat or a material-mean-specific-heat in kB/spin.  The kB is the Boltzmann constant [4].

Since 1 kB = 1.380649×10^(-23) J/K, that should make it easy to convert kB/spin to J/K/spin.

The more challenging part might be how to get spin to kg.

Maybe you could assume 1 spin equals 1 atom.  If so, from the geometry of the cell that you've specified in the VAMPIRE simulation, you likely could determine the atomic density [5] in units of atoms/cell_volume.

From that, I think could get the volumetric heat capacity.  Then, according to [6], the volumetric heat capacity can multiplied by the material or mass density to express the heat capacity per unit of mass (i.e., units of JK-1kg-1).

Hopefully that can help.

[1] https://groups.google.com/g/vampire-users/c/iGW0CYSnSDA/m/BfbNOgNkFQAJ

[2] https://en.wikipedia.org/wiki/Dimensional_analysis

[3] https://groups.google.com/g/vampire-users/c/gW0NeAJIjvc/m/UxbuABa0CgAJ

[4] https://en.wikipedia.org/wiki/Boltzmann_constant

[5] https://www.nuclear-power.com/nuclear-power/reactor-physics/nuclear-engineering-fundamentals/neutron-nuclear-reactions/atomic-number-density/

[6] https://en.wikipedia.org/wiki/Volumetric_heat_capacity

Kind Regards,

Gavin

VAMPIRE user