Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA.
Department of Physics, University of Illinois at Urbana-Champaign, 1100 West Green Street, Urbana, Illinois 61801, USA.
J Chem Phys. 2014 Jan 14;140(2):024702. doi: 10.1063/1.4859257.
Finite-temperature extensions of ab initio Gaussian-basis-set spin-restricted Hartree-Fock (HF) and second-order many-body perturbation (MP2) theories are implemented for infinitely extended, periodic, one-dimensional solids and applied to the Peierls and charge-density-wave (CDW) transitions in polyyne and all-trans polyacetylene. The HF theory predicts insulating CDW ground states for both systems in their equidistant structures at low temperatures. In the same structures, they turn metallic at high temperatures. Starting from the "dimerized" low-temperature equilibrium structures, the systems need even higher temperatures to undergo a Peierls transition, which is accompanied by geometric as well as electronic distortions from dimerized to non-dimerized forms. The conventional finite-temperature MP2 theory shows a sign of divergence in any phase at any nonzero temperature and is useless. The renormalized finite-temperature MP2 (MP2R) theory is divergent only near metallic electronic structures, but is well behaved elsewhere. MP2R also predicts CDW and Peierls transitions occurring at two different temperatures. The effect of electron correlation is primarily to lower the Peierls transition temperature.
我们实现了无限延伸的、周期性的一维固体的从头算高斯基组限制 Hartree-Fock(HF)和二阶多体微扰(MP2)理论的有限温度扩展,并将其应用于聚乙炔和全反式聚乙炔中的 Peierls 和电荷密度波(CDW)转变。HF 理论预测,在低温下等距结构中,这两个体系的 CDW 基态都是绝缘的。在相同的结构中,它们在高温下变成金属。从“二聚化”的低温平衡结构开始,系统需要更高的温度才能经历 Peierls 转变,这伴随着从二聚化到非二聚化形式的几何和电子变形。传统的有限温度 MP2 理论在任何非零温度的任何相中都显示出发散的迹象,因此毫无用处。正则化有限温度 MP2(MP2R)理论仅在金属电子结构附近发散,但在其他地方表现良好。MP2R 还预测 CDW 和 Peierls 转变发生在两个不同的温度。电子相关的主要作用是降低 Peierls 转变温度。