Gorelov Vitaly, Ceperley David M, Holzmann Markus, Pierleoni Carlo
Maison de la Simulation, CEA, CNRS, Univ. Paris-Sud, UVSQ, Université Paris-Saclay, 91191 Gif-sur-Yvette, France.
Department of Physics, University of Illinois, Urbana, Illinois 61801, USA.
J Chem Phys. 2020 Dec 21;153(23):234117. doi: 10.1063/5.0031843.
We develop a formalism to accurately account for the renormalization of the electronic structure due to quantum and thermal nuclear motions within the Born-Oppenheimer approximation. We focus on the fundamental energy gap obtained from electronic addition and removal energies from quantum Monte Carlo calculations in either the canonical or grand-canonical ensembles. The formalism applies as well to effective single electron theories such as those based on density functional theory. We show that the electronic (Bloch) crystal momentum can be restored by marginalizing the total electron-ion wave function with respect to the nuclear equilibrium distribution, and we describe an explicit procedure to establish the band structure of electronic excitations for quantum crystals within the Born-Oppenheimer approximation. Based on the Kubo-Greenwood equation, we discuss the effects of nuclear motion on optical conductivity. Our methodology applies to the low temperature regime where nuclear motion is quantized and, in general, differs from the semi-classical approximation. We apply our method to study the electronic structure of C2/c-24 crystalline hydrogen at 200 K and 250 GPa and discuss the optical absorption profile of hydrogen crystals at 200 K and carbon diamond at 297 K.
我们开发了一种形式体系，以在玻恩 - 奥本海默近似下精确考虑由于量子和热核运动导致的电子结构重整化。我们关注从量子蒙特卡罗计算中在正则或巨正则系综下的电子添加和去除能量所获得的基本能隙。该形式体系同样适用于诸如基于密度泛函理论的有效单电子理论。我们表明，通过相对于核平衡分布对总电子 - 离子波函数进行边缘化处理，可以恢复电子（布洛赫）晶体动量，并且我们描述了一种明确的程序，用于在玻恩 - 奥本海默近似下确定量子晶体电子激发的能带结构。基于久保 - 格林伍德方程，我们讨论了核运动对光导率的影响。我们的方法适用于核运动被量子化的低温区域，并且一般来说与半经典近似不同。我们应用我们的方法来研究200 K和250 GPa下C2/c - 24晶体氢的电子结构，并讨论200 K下氢晶体和297 K下碳金刚石的光吸收谱。
