Homocoordination preference in NaCs and LiNa liquid alloys by first principles molecular dynamics

Abstract

We present structural and dynamics results based on Hellman-Feynman molecular dynamics for the liquid phase of the NaCs alloy at two Na concentrations (c Na ϭ0.6 and 0.8͒ and for the Li 0.61 Na 0.39 zero alloy at two temperatures (Tϭ590 K and 690 K͒. For NaCs the calculated structure factor S(k) is in very good agreement with data from neutron scattering experiments and the partial structure factors are compared to semiexperimental, theoretical and classical molecular dynamics predictions. We predict similar values for the self-diffusion coefficients of Na and Cs atoms in the Na 0.6 Cs 0.4 alloy. For LiNa the concentration-concentration structure factor is in good agreement with experimental data and our results for the dynamics are compared with data from classical molecular dynamics simulations.

Pseudopotentials for the calculation of dynamic properties of liquids

“…Hoshino and co-workers [71] used 100 atoms with an energy cut-off of 10 Ryd, and their S(k) seems to reproduce the main experimental features, although the results are extremely noisy. Also, Costa Cabral and Martins [72] have used 108 atoms with an energy cut-off of 9 Ryd and similar non-local pseudopotentials, and the properties were obtained by averaging over 300-400 configurations. Their S(k) qualitatively reproduces the experimental one, although quantitative differences appear over the whole k-region (see figure 7).…”

“…Figure 7 shows the Bhatia-Thornton partial structure factors obtained (numbernumber S NN (k), concentration-concentration S cc (k), and number-concentration S Nc (k)), and the total neutron weighted structure factor S(k). For comparison, we include the LRT-CMD results of Canales et al [69] and the KS-AIMD results of Costa Cabral and Martins [72] along with the experimental data. The present results show an excellent agreement with experiment, improving on the KS-AIMD results and also the already good LRT-CMD results.…”

“…Open circles: experimental neutron diffraction data. Dashed line: KS-AIMD results[72]. Long-dashed line: LRT-CMD results[69].…”

Liquid metals: early contributions and some recent developments

“…In the late nineties, numerous AIMD studies of multicomponent alloys of simple metals, less simple and transitions ones were conducted by different groups. A review of this work is beyond the scope of this contribution -see for example [87][88][89][90] and references therein. In the last section, we discuss some problems raised by such simulations.…”