論文名 Variational quantum eigensolver simulations with the multireference unitary coupled cluster ansatz : a case study of the C_2v quasi-reaction pathway of beryllium insertion into a H_2 molecule
記事種別等 Paper
著者名 著者名（別言語） 杉崎, 研司 / 加藤, 拓己 / 湊, 雄一郎 / 奥脇, 弘次 / 望月, 祐志
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この文献へのリンクには次のURLを使用してください 抄録・内容（英） Variational quantum eigensolver (VQE)-based quantum chemical calculations have been extensively studied as a computational model using noisy intermediate-scale quantum devices. The VQE uses a parametrized quantum circuit defined through an "ansatz" to generate approximated wave functions, and the appropriate choice of an ansatz is the most important step. Because most chemistry problems focus on the energy difference between two electronic states or structures, calculating the total energies in different molecular structures with the same accuracy is essential to correctly understand chemistry and chemical processes. In this context, the development of ansatzes that are capable of describing electronic structures of strongly correlated systems accurately is an important task. Here we applied a conventional unitary coupled cluster (UCC) and a newly developed multireference unitary coupled cluster with partially generalized singles and doubles (MR-UCCpGSD) ansatzes to the quasi-reaction pathway of Be insertion into H_2, LiH molecule under covalent bond dissociation, and a rectangular tetra-hydrogen cluster known as a P4 cluster; these are representative systems in which the static electron correlation effect is prominent. Our numerical simulations revealed that the UCCSD ansatz exhibits extremely slow convergence behaviour around the point where an avoided crossing occurs in the Be + H_2 → BeH_2 reaction pathway, resulting in a large discrepancy of the simulated VQE energy from the full-configuration interaction (full-CI) value. By contrast, the MR-UCCpGSD ansatz can give more reliable results with respect to total energy and the overlap with the full-CI solution, insisting the importance of multiconfigurational treatments in the calculations of strongly correlated systems. The MR-UCCpGSD ansatz allows us to compute the energy with the same accuracy regardless of the strength of multiconfigurational character, which is an essential property to discuss energy differences of various molecular systems.
備考 This work was supported by JSPS KAKENHI Scientific Research C (Grant No. 18K03465 and 21K03407).
言語 eng
ページ開始 8439
ページ終了 8452
キーワード（日） キーワード（英） 著者版フラグ publisher
著者所属（英） Osaka City University, JST PRESTO, TCG Centres for Research and Education in Science and Technology / Blueqat Inc. / Blueqat Inc. / Rikkyo University / Rikkyo University, The University of Tokyo
1人目の著者情報 : KAKEN 1人目の著者情報 : その他 4人目の著者情報 : その他 5人目の著者情報 : KAKEN 5人目の著者情報 : その他 収録物名 巻 号 刊行年月 2022-04-14
出版社 Royal Society of Chemistry
ISSN 1463-9084
雑誌書誌ID（NII) AA11723355
資料種別 資料種別(英語) Journal Article
DOI https://doi.org/10.1039/D1CP04318H
権利 This Open Access Article is licensed under a Creative Commons Attribution 3.0. Unported Licence. https://creativecommons.org/licenses/by/3.0/
