无公度固体~ 4 He的弹性常数
Elastic Constants of Incommensurate Solid 4He
摘要：
研究了零温极限下无公度固体~ 4 He的弹性性质。具体地说，我们计算的五个弹性常数（C11，C12，C13，C33，和C44），纵向和横向声速的压力依赖性，以及T = 0德拜温度的无公度和公度hcp 4 He使用扩散蒙特卡罗方法。我们的研究结果表明，在压缩下的公度晶体是全球刚性比非公度，然而，在压力接近熔化（即P ~ 25巴）的一些弹性常数占的hcp基面（C12和C13）的应变变形的非公度固体略大。此外，我们发现，在引入微小浓度的点缺陷的剪切模量的4 He（C44）经历了一个小的减少。
英文摘要：
We study the elastic properties of incommensurate solid 4He in the limit of zero temperature. Specifically, we calculate the pressure dependence of the five elastic constants (C11, C12, C13, C33, and C44), longitudinal and transversal speeds of sound, and the T = 0 Debye temperature of incommensurate and commensurate hcp 4He using the diffusion Monte Carlo method. Our results show that under compression the commensurate crystal is globally stiffer than the incommensurate, however at pressures close to melting (i.e. P ~ 25 bars) some of the elastic constants accounting for strain deformations of the hcp basal plane (C12 and C13) are slightly larger in the incommensurate solid. Also, we find that upon the introduction of tiny concentrations of point defects the shear modulus of 4He (C44) undergoes a small reduction.
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