A multireference picture of electronic excited states in vanadyl and copper tetraphenyl porphyrin molecular qubits

Fuente: arXiv
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Main Authors: Sarkar, Arup, Lunghi, Alessandro
Format: Preprint
Published: 2025
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author Sarkar, Arup
Lunghi, Alessandro
author_facet Sarkar, Arup
Lunghi, Alessandro
contents The nature of electronic excited states has a deep impact on the dynamics of molecular spins, but remains poorly understood and characterized. Here we carry out a thorough multiconfigurational investigation for two prototypical molecular qubits based on vanadyl and copper tetra-phenyl porphyrins. State-average CASSCF and NEVPT2 calculations have been employed with four different active spaces of growing complexity to account for the d-d, second d-shell, ligand-to-metal charge transfer states and $π-π^*$ excited states, revealing an in-depth picture of low-lying excited states in agreement with experimental observations. The largest active spaces attempted, (13,14) for the vanadyl and (17,12) for the copper compounds, reveal that the lowest-lying excited states originate from $π-π^*$ quartet excitations. These findings shed light on the nature of the excited states of molecular qubits, taking an important step toward elucidating their role in molecular spin dynamics.
format Preprint
id arxiv_https___arxiv_org_abs_2504_20778
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A multireference picture of electronic excited states in vanadyl and copper tetraphenyl porphyrin molecular qubits
Sarkar, Arup
Lunghi, Alessandro
Quantum Physics
Materials Science
The nature of electronic excited states has a deep impact on the dynamics of molecular spins, but remains poorly understood and characterized. Here we carry out a thorough multiconfigurational investigation for two prototypical molecular qubits based on vanadyl and copper tetra-phenyl porphyrins. State-average CASSCF and NEVPT2 calculations have been employed with four different active spaces of growing complexity to account for the d-d, second d-shell, ligand-to-metal charge transfer states and $π-π^*$ excited states, revealing an in-depth picture of low-lying excited states in agreement with experimental observations. The largest active spaces attempted, (13,14) for the vanadyl and (17,12) for the copper compounds, reveal that the lowest-lying excited states originate from $π-π^*$ quartet excitations. These findings shed light on the nature of the excited states of molecular qubits, taking an important step toward elucidating their role in molecular spin dynamics.
title A multireference picture of electronic excited states in vanadyl and copper tetraphenyl porphyrin molecular qubits
topic Quantum Physics
Materials Science
url https://arxiv.org/abs/2504.20778