Ab-initio Molecular Dynamics Study Of Structure And Dynamic Properties Of Liquid Metal

The melting process of pure Fe, the structures and dynamic properties of liquid Feand Cu₆₄Zr₃₆binary alloy are investigated in this paper using the ab initio moleculardynamics （AIMD） method.In the process of temperature rise, the energy of liquid Fe increases and Fe melts at1500K. The structure becomes disorderly with temperature rising. We investigate theliquid Fe at different temperatures and note that the structure of liquid Fe becomes moreorderly at lower temperatures compared with high temperatures and local icosahedralshort-range order （ISRO） is dominant with temperature decreasing. ISRO in liquid Feand its effects on slowing dynamics are also analysed. Our results confirm that thequantity of icosahedrons increases upon cooling accompanying with the slowingdynamic, indicating that the ISRO atoms have weak rearrangement ability comparedwith the whole atoms. More importantly, by detailed dynamics analysis, we find that theeffecting-time of icosahedron which slows down the dynamics is not restricted in theβ-relaxation region, but lasts to the time that Fs（qmax,t） decayed to around0.1which is inthe deep α-relaxation region.We investigate the structures and dynamic properties of liquid Cu₆₄Zr₃₆alloy bycalculate the radial distribution function g（r）, the static structure factor S（q）, themean-square displacement MSD and the incoherent intermediate scattering functionF_s(q_max,t). Our results confirm that the order degree of structure increases withdecreasing temperature; the structure changes with temperature of liquid Cu₆₄Zr₃₆alloyis related to Cu-Zr and Cu-Cu atomic arrangements; the particles move more slowly atlow temperature and the motion of Cu atoms promotes the development of the dynamicsof liquid Cu₆₄Zr₃₆alloy.