摘要
在共振价键理论基础上,选取高压液氢电子主要占据轨道的线性组合作为基组,构建由Jastrow项和反对称孪生函数乘积项(AGP)组成的波函数.考虑电子关联作用的共振价键(RVB)波函数得出的能量值低于LDA能量值;当满足rs<1.75或T>15000K时引入back flow项以改善波函数结点面,改善后的能量值下降约1mHa/atom,能量方差值变小.将构建的RVB波函数与电子-离子耦合的蒙特卡罗法(CEIMC)相结合,计算结果与实验及其他ab-initio结果相符合,获得的液氘单次冲击Hugoniot曲线基本通过所有加载类型实验误差棒,液氘在50.3GPa处具有最大压缩率4.48,在100—120GPa内未发现压缩率有急剧增大的现象.构建的RVB波函数能够适用于较宽密度与温度范围内(1.0<rs<2.2,2800K<T<60000K)液氢的模拟,与CEIMC法相结合可提高液氢冲击特性的模拟精度.
Based on the resonating valence bond theory, the linear combinations of the main orbits occupied by liquid hydrogen electrons are selected as the basis sets to construct the Jastrow antisymmetrized geminal product. The resonating valence bond （RVB） wave function which takes into consideration electron correlation effects provides lower energy than the local density approximation （LDA） function. In order to improve the nodal accuracy of the variational trial wave function, the backflow correlations are suggested to be employed whenever rs 1.75 or T 15000 K, the improved wave function has about 1 mHa/atom decrease in local energy with respect to the one without backflow effects at the VMC level, and has a lower variance simultaneity. After combining the coupled electronion Monte Carlo （CEIMC） method with the RVB wave function, the simulation results we have obtained are in good agreement with the experimental and other ab-initio ones; the deuterium principal Hugoniot curve passing through the error bars of various existing experiments conducted via different high-pressure technologies has a maximum compression of 4.48 at about 50.3GPa, but the phenomenon of apparent increase in compression ratio along the Hugoniot between 100—120 GPa has not been found. The RVB wave function discussed in this paper when adopted the CEIMC method is not only quite suitable for the simulation of liquid hydrogen within a wide range of density and temperature （1.0 rs 2.2, 2800 K T 60000 K）, but also can give some more applicable thermodynamic properties of hydrogen under shock loading.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2013年第15期289-297,共9页
Acta Physica Sinica
关键词
共振价键理论
波函数
量子蒙卡法
液氢
resonating valence bond theory
wave function
QMC method
liquid hydrogen
