Exploring Spin Symmetry-Breaking Effects for Static Field Ionization of Atoms: Is There an Analog to the Coulson-Fischer Point in Bond Dissociation?
arXiv:2106.04040 · doi:10.1063/5.0054387
Abstract
Löwdin's symmetry dilemma is an ubiquitous issue in approximate quantum chemistry. In the context of Hartree-Fock (HF) theory, the use of Slater determinants with some imposed constraints to preserve symmetries of the exact problem may lead to physically unreasonable potential energy surfaces. On the other hand, lifting these constraints leads to the so-called broken symmetry solutions that usually provide better energetics, at the cost of losing information about good quantum numbers that describe the state of the system. This behavior has been previously extensively studied in the context of bond dissociation. This paper studies the behavior of different classes of Hartree-Fock spin polarized solutions (restricted, unrestricted, generalized) in the context of ionization by strong static electric fields. We find that, for simple two-electron systems, UHF is able to provide a qualitatively good description of states involved during the ionization process (neutral, singly-ionized and doubly ionized states), whereas RHF fails to describe the singly ionized state. For more complex systems, even though UHF is able to capture some of the expected characteristics of the ionized states, it is constrained to a single (diabatic) manifold in the energy surface as a function of field intensity. In this case a better qualitative picture can be painted by GHF as it is able to explore different spin manifolds and follow the lowest solution due to lack of collinearity constraints on the spin quantization axis.
References in corpus (21)
- Photoelectron angular distributions from strong-field ionization of oriented molecules
- Attosecond physics at the nanoscale
- Breakdown of the Dipole Approximation in Strong-Field Ionization
- Semiclassical two-step model for strong-field ionization
- Canonical-basis time-dependent Hartree-Fock-Bogoliubov theory and linear-response calculations
- Ab initio quantum dynamics using coupled-cluster
- Regularized Orbital-Optimized Second-Order Møller-Plesset Perturbation Theory: A Reliable Fifth-Order Scaling Electron Correlation Model with Orbital Energy Dependent Regularizers
- Magnetic fields alter tunneling in strong-field ionization
- Symmetry restoration in Hartree-Fock-Bogoliubov based theories
- Coupled-cluster theory for atoms and molecules in strong magnetic fields
- Symplectic integration and physical interpretation of time-dependent coupled-cluster theory
- Distinguishing Artificial and Essential Symmetry Breaking in a Single Determinant: Approach and Application to the C, C, and C Fullerenes
- Two Single-Reference Approaches to Singlet Biradicaloid Problems: Complex, Restricted Orbitals and Approximate Spin-Projection Combined With Regularized Orbital-Optimized Møller-Plesset Perturbation Theory
- Polyradical character and spin frustration in fullerene molecules: An ab initio non-collinear Hartree--Fock study
- Well-behaved versus ill-behaved density functionals for single bond dissociation: Separating success from disaster functional by functional for stretched H
- Point symmetries in the Hartree-Fock approach: Symmetry-breaking schemes
- Beyond the Coulson-Fischer point: Characterizing single excitation CI and TDDFT for excited states in single bond dissociations
- Kohn-Sham Density Functional Theory with Complex, Spin-Restricted Orbitals: Accessing a New Class of Densities without the Symmetry Dilemma
- Numerical stability of time-dependent coupled-cluster methods for many-electron dynamics in intense laser pulses
- Coupled-cluster treatment of molecular strong-field ionization
- Time-dependent optimized coupled-cluster method for multielectron dynamics III: A second-order many-body perturbation approximation