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Main Authors: Sugisaki, Kenji, Nakano, Tatsuya, Mochizuki, Yuji
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2402.17993
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author Sugisaki, Kenji
Nakano, Tatsuya
Mochizuki, Yuji
author_facet Sugisaki, Kenji
Nakano, Tatsuya
Mochizuki, Yuji
contents The fragment molecular orbital (FMO) scheme is one of the popular fragmentation-based methods and has the potential advantage of making the circuit flat in quantum chemical calculations on quantum computers. In this study, we used a GPU-accelerated quantum simulator (cuQuantum) to perform the electron correlation part of the FMO calculation as unitary coupled-cluster singles and doubles (UCCSD) with the variational quantum eigensolver (VQE) for hydrogen-bonded (FH)$_3$ and (FH)$_2$-H$_2$O systems with the STO-3G basis set. VQE-UCCD calculations were performed using both canonical and localized MO sets, and the results were examined from the point of view of size-consistency and orbital-invariance affected by the Trotter error. It was found that the use of localized MO leads to better results, especially for (FH)$_2$-H$_2$O. The GPU acceleration was substantial for the simulations with larger numbers of qubits, and was about a factor of 6.7--7.7 for 18 qubit systems.
format Preprint
id arxiv_https___arxiv_org_abs_2402_17993
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Size-consistency and orbital-invariance issues revealed by VQE-UCCSD calculations with the FMO scheme
Sugisaki, Kenji
Nakano, Tatsuya
Mochizuki, Yuji
Quantum Physics
Chemical Physics
The fragment molecular orbital (FMO) scheme is one of the popular fragmentation-based methods and has the potential advantage of making the circuit flat in quantum chemical calculations on quantum computers. In this study, we used a GPU-accelerated quantum simulator (cuQuantum) to perform the electron correlation part of the FMO calculation as unitary coupled-cluster singles and doubles (UCCSD) with the variational quantum eigensolver (VQE) for hydrogen-bonded (FH)$_3$ and (FH)$_2$-H$_2$O systems with the STO-3G basis set. VQE-UCCD calculations were performed using both canonical and localized MO sets, and the results were examined from the point of view of size-consistency and orbital-invariance affected by the Trotter error. It was found that the use of localized MO leads to better results, especially for (FH)$_2$-H$_2$O. The GPU acceleration was substantial for the simulations with larger numbers of qubits, and was about a factor of 6.7--7.7 for 18 qubit systems.
title Size-consistency and orbital-invariance issues revealed by VQE-UCCSD calculations with the FMO scheme
topic Quantum Physics
Chemical Physics
url https://arxiv.org/abs/2402.17993