Electrical and thermal conductivity of liquid sodium from firstprinciples calculations
Abstract
We report on the electrical and thermal conductivity of liquid sodium at 400 K, calculated using density functional theory with the local density approximation (LDA) and the KuboGreenwood formula. We extensively tested systemsize errors and kpoint sampling, using simulation cells containing up to 2000 atoms. We find that convergence of the results with respect to the size of the system is slow, and at least 1024atom systems are required to obtain conductivities converged to within a few percent. Γpoint sampling does not seem to be accurate enough, even for the very largest 2000atom system. We performed calculations at three densities, including the experimental density ρ_{expt}=921 kg m^{3}, the LDA density ρ_{LDA}=1046 kg m^{3}, and a higher density ρ=1094 kg m^{3}. At the experimental density, the electrical conductivity is underestimated by ∼35%, at the LDA density it is overestimated by ∼18%, and at the largest density it is higher than the experimental one by ∼50%. At the experimental density, we also used the PerdewBurkeErnzerhof functional, and found that the conductivity is overestimated by only ∼6%.
 Publication:

Physical Review B
 Pub Date:
 August 2011
 DOI:
 10.1103/PhysRevB.84.054203
 Bibcode:
 2011PhRvB..84e4203P
 Keywords:

 72.15.Cz;
 71.15.m;
 65.20.w;
 Electrical and thermal conduction in amorphous and liquid metals and alloys;
 Methods of electronic structure calculations;
 Thermal properties of liquids