Tree Tensor Networks Methods for Efficient Calculation of Molecular Vibrational Spectra

Fuente: arXiv
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Main Authors: Sun, Shuo, Milbradt, Richard M., Knecht, Stefan, Kumar, Chandan, Mendl, Christian B.
Format: Preprint
Published: 2025
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author Sun, Shuo
Milbradt, Richard M.
Knecht, Stefan
Kumar, Chandan
Mendl, Christian B.
author_facet Sun, Shuo
Milbradt, Richard M.
Knecht, Stefan
Kumar, Chandan
Mendl, Christian B.
contents We develop and employ general Tree Tensor Networks (TTNs) to compute the vibrational spectra for two model systems: a set of 64-dimensional coupled oscillators and acetonitrile. We explore various tree architectures, ranging from the simple linear structure of Matrix Product States (MPS), to trees where only the leaf nodes carry a physical leg -- as seen in the underlying ansatz of the Multilayer Multiconfiguration Time-Dependent Hartree (ML-MCTDH) method -- and further to more general trees in which all nodes are allowed to possess a physical leg. In addition, we implement Locally Optimal Block Preconditioned Conjugate Gradient (LOBPCG) methods and Inverse Iteration methods as eigensolvers. By means of comprehensive benchmarking of runtime and accuracy, we demonstrate that sub-wavenumber accuracy in vibrational spectra is achievable with all TTN structures. MPS and three-legged tree tensor network states (T3NS) have similar runtimes, whereas leaf-only trees require significantly more time. All numerical simulations were performed using PyTreeNet, a Python package designed for flexible tensor network computations.
format Preprint
id arxiv_https___arxiv_org_abs_2512_15875
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Tree Tensor Networks Methods for Efficient Calculation of Molecular Vibrational Spectra
Sun, Shuo
Milbradt, Richard M.
Knecht, Stefan
Kumar, Chandan
Mendl, Christian B.
Chemical Physics
Quantum Physics
We develop and employ general Tree Tensor Networks (TTNs) to compute the vibrational spectra for two model systems: a set of 64-dimensional coupled oscillators and acetonitrile. We explore various tree architectures, ranging from the simple linear structure of Matrix Product States (MPS), to trees where only the leaf nodes carry a physical leg -- as seen in the underlying ansatz of the Multilayer Multiconfiguration Time-Dependent Hartree (ML-MCTDH) method -- and further to more general trees in which all nodes are allowed to possess a physical leg. In addition, we implement Locally Optimal Block Preconditioned Conjugate Gradient (LOBPCG) methods and Inverse Iteration methods as eigensolvers. By means of comprehensive benchmarking of runtime and accuracy, we demonstrate that sub-wavenumber accuracy in vibrational spectra is achievable with all TTN structures. MPS and three-legged tree tensor network states (T3NS) have similar runtimes, whereas leaf-only trees require significantly more time. All numerical simulations were performed using PyTreeNet, a Python package designed for flexible tensor network computations.
title Tree Tensor Networks Methods for Efficient Calculation of Molecular Vibrational Spectra
topic Chemical Physics
Quantum Physics
url https://arxiv.org/abs/2512.15875