Excitations in photoactive molecules from quantum Monte Carlo

Abstract

Despite significant advances in electronic structure methods for the treatment of excited states, attaining an accurate description of the photoinduced processes in photoactive biomolecules is proving very difficult. For the prototypical photosensitive molecules, formaldimine, formaldehyde and a minimal protonated Schiff base model of the retinal chromophore, we investigate the performance of various approaches generally considered promising for the computation of excited potential energy surfaces. We show that quantum Monte Carlo can accurately estimate the excitation energies of the studied systems if one constructs carefully the trial wave function, including in most cases the reoptimization of its determinantal part within quantum Monte Carlo. While time-dependent density functional theory and quantum Monte Carlo are generally in reasonable agreement, they yield a qualitatively different description of the isomerization of the Schiff base model. Finally, we find that the restricted open shell Kohn-Sham method is at variance with quantum Monte Carlo in estimating the lowest-singlet excited state potential energy surface for low-symmetry molecular structures.

10 pages, 6 figures

References in corpus (4)

• Separable Dual Space Gaussian Pseudo-potentials
• High Accuracy Many-Body Calculational Approaches for Excitations in Molecules
• Optimized Jastrow-Slater wave functions for ground and excited states: Application to the lowest states of ethene
• Optimization of inhomogeneous electron correlation factors in periodic solids

Cited by in corpus (15)

• Continuum variational and diffusion quantum Monte Carlo calculations
• A Mountaineering Strategy to Excited States: Highly-Accurate Reference Energies and Benchmarks
• Troubleshooting Time-Dependent Density-Functional Theory for Photochemical Applications: Oxirane
• An excited-state approach within full configuration interaction quantum Monte Carlo
• Excitation energies from diffusion Monte Carlo using selected Configuration Interaction nodes
• Excited state calculations using phaseless auxiliary-field quantum Monte Carlo: potential energy curves of low lying C2 singlet states
• Excited states with selected CI-QMC: chemically accurate excitation energies and geometries
• Excited state calculations in solids by auxiliary-field quantum Monte Carlo
• Excited State Specific Multi-Slater Jastrow Wave Functions
• Influence of Pseudopotentials on Excitation Energies From Selected Configuration Interaction and Diffusion Monte Carlo
• Excited-state diffusion Monte Carlo calculations: a simple and efficient two-determinant ansatz
• Quantum Monte Carlo for minimum energy structures
• Ground and Excited States from Ensemble Variational Principles
• Charge-transfer excited states: Seeking a balanced and efficient wave function ansatz in variational Monte Carlo
• Systematic reduction of sign errors in many-body problems: generalization of self-healing diffusion Monte Carlo to excited states