液体金属イオン系の熱運動の計算機シミュレーション：自己拡散機構と集団熱運動の解析

抄録

Characteristics of the thermal motions of ions in a model of liquid Na near the melting point are investigated using the simulation of the molecular dynamics first developed by A. Rahman.
The first half of the note is devoted to report a manual of the simulation of the LRO-II pair-potential system. Examination on the equilibrium conditions of the small system (N=864) and the ergodicity of the average over the file of motion of the system proves that the accuracy of the file made by the use of a home-manufactured computer (NEAC 2200, model 700) is comparable to that obtained by IBM, CDC 6600, etc.
In the last half, characteristics of the thermal motions of Na ions are investigated. It has been made clear that the thermal diffusion of an individual ion is not the jumping diffusion type but a smooth oscillatory migration type. This motion is considered to be cooperative with 10∼15 surrounding ions, i.e. the first shell neighbours in the sense of g(r). These local collective motions correspond to the characteristic peaks in the dynamic structure factor S(Q,ω) of the neutron inelastic scattering around 10¹³ rad/sec in the value of ω.