Kanayama Kansei, Toyoura Kazuaki
Department of Materials Science and Engineering, Kyoto University, Kyoto 606-8501, Japan.
J Phys Condens Matter. 2024 Aug 7;36(44). doi: 10.1088/1361-648X/ad68b0.
First-principles molecular dynamics (FPMD) simulations were applied for analyzing structural evolutions around the paraelectric-ferroelectric phase transition temperature in the perovskite-type cadmium titanate, CdTiO. Since the phase transition is reported to occur at the low temperature around 80 K, the quantum thermal bath (QTB) method was utilized in this study, which incorporates the nuclear quantum effects (NQEs). The structural evolutions in the QTB-FPMD simulations are in reasonable agreement with the experimental results, by contrast in the conventional FPMD simulations using the classical thermal bath (CTB-FPMD). Especially, the non-linear thermal expansion of lattice constants around the phase transition temperature was well reproduced in the QTB-FPMD with the NQEs. Thus, the NQEs are of importance in phase transitions at low temperatures, particularly below the room temperature, and the QTB is useful in that it incorporates the NQEs in MD simulations with low computational costs comparable to the conventional CTB.
第一性原理分子动力学（FPMD）模拟被用于分析钙钛矿型钛酸镉（CdTiO₃）中顺电-铁电相变温度附近的结构演变。由于据报道该相变发生在约80K的低温下，本研究采用了包含核量子效应（NQEs）的量子热浴（QTB）方法。与使用经典热浴的传统FPMD模拟（CTB-FPMD）相比，QTB-FPMD模拟中的结构演变与实验结果合理吻合。特别是，在考虑NQEs的QTB-FPMD中，相变温度附近晶格常数的非线性热膨胀得到了很好的再现。因此，NQEs在低温特别是室温以下的相变中很重要，并且QTB很有用，因为它能在计算成本与传统CTB相当低的MD模拟中纳入NQEs。
