A simple theoretical model for evaluating the ability to form a single crystal

A simple theoretical model proposed recently to evaluate the ability of bulk materials to form single crystals is further tested via vast molecular dynamics simulations of growth for fcc (Ni,Cu,Al,Ar) and hcp (Mg) crystals,especially applied to the growth of bcc (Fe) crystal,showing that the validity of the model is independent of crystal types and the interaction potentials of the constitute atoms.     

A Simple Theoretical Method to Predict the Hardness of Pure Metal Crystals

Design of superhard bulk materials requires predicting their hardness, challenging current theories for material design. By introducing a concept of condensing force （CF）, it is shown via ab initio calculations for fcc （Ni, Cu, Al, Ir, Rh, Au, Ag, Pd） and hcp Re crystals that materials with larger CF can have greater hardness. Since the calculation of CF is easy, this method might prove a convenient way to evaluate the hardness of newly designed materials.     

基于N2 LBH带的中高层大气氧分子柱密度反演

给出了一种利用气辉探测反演中高层大气氧分子柱密度的新方法。氧分子对N₂ Lyman-Birge-Hopfield (LBH)短波带(LBH_S)的吸收作用较强,而对N₂ LBH长波带(LBH_L)的吸收作用较弱,根据这一特性,利用N₂ LBH_S与N₂ LBH_L的比值来反演中高层大气氧分子柱密度。通过气辉模型计算得到一个用于估计氧气含量的插值表,计算得到在不同氧分子柱密度、不同太阳天顶角、卫星观测角和太阳活动条件下的N₂ LBH长短波带比值的自然对数ln(LBH_S/LBH_L),根据探测的ln(LBH_S/LBH_L)及相应的太阳天顶角、卫星观测角和太阳活动指数,拟合得到氧分子柱密度。最后,采用模式模拟的方法对反演结果进行验证,所得反演结果与模拟真值的误差在百分之十以内,证明了这种探测中高层大气氧分子柱密度新途径的可行性。