Orthogonally Constrained Orbital Optimization: assessing changes of optimal orbitals for orthogonal multi-reference states

• URL: http://arxiv.org/abs/2211.08329v1
• Date: Tue, 15 Nov 2022 17:39:39 GMT
• Title: Orthogonally Constrained Orbital Optimization: assessing changes of optimal orbitals for orthogonal multi-reference states
• Authors: Saad Yalouz and Vincent Robert
• Abstract summary: The choice of molecular orbitals is decisive in configuration interaction calculations. The approach faithfully recovers the energy of afour-electron Hubbard trimer, whereas state-average calculations can miss the value by a factor 2.5.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: The choice of molecular orbitals is decisive in configuration interaction calculations. In this letter, a democratic description of the ground and excited states follows an orthogonally constrained orbitals optimization to produce state-specific orbitals. The approach faithfully recovers the excitation energy of afour-electron Hubbard trimer, whereas state-average calculations can miss the value by a factor 2.5. The method emphasises the need for orbitals optimizationto reduce expansions and to reach spectroscopic accuracy.

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