Excited states in variational Monte Carlo using a penalty method

Abstract

The authors present a technique using variational Monte Carlo to solve for excited states of electronic systems. The technique is based on enforcing orthogonality to lower energy states, which results in a simple variational principle for the excited states. Energy optimization is then used to solve for the excited states. This technique is applied to the well-characterized benzene molecule, in which $\sim$10,000 parameters are optimized for the first 12 excited states. Agreement within approximately 0.2 eV is obtained with higher scaling coupled cluster methods; small disagreements with experiment are likely due to vibrational effects.

References in corpus (4)

• Inhomogeneous backflow transformations in quantum Monte Carlo calculations
• Role of backflow correlations for the non-magnetic phase of the t-t' Hubbard model
• Direct comparison of many-body methods for realistic electronic Hamiltonians
• Improving excited state potential energy surfaces via optimal orbital shapes

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• PyQMC: an all-Python real-space quantum Monte Carlo module in PySCF
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• Neutral band gap of carbon by quantum Monte Carlo methods
• Modal Backflow Neural Quantum States for Anharmonic Vibrational Calculations
• Orthogonally Constrained CASSCF Framework: Newton-Raphson Orbital Optimization and Nuclear Gradients
• Electronic excited states in deep variational Monte Carlo
• Excitations of Quantum Many-Body Systems via Purified Ensembles: A Unitary-Coupled-Cluster-based Approach
• One-Body Properties and Their Perturbative Accuracy with Aufbau Suppressed Coupled Cluster Theory