Dynamic electron correlation is very important for the correct description of potential energy surfaces, especially for surfaces with differential dynamic electron correlation. An accurate description of both the ground and excited state potential energy surfaces is essential to understand thermal and photochemical reactions of molecular systems. A challenging test system for the assessment of electronic-structure methods is a minimal model of the chromophore of rhodopsin, the penta-2,4-dieniminium cation (PSB3). In particular, it is suitable for the exploration of ground- and excited-state potential-energy surfaces, the topography of conical intersections, and the dimensionality of the branching space. We have tested the performance of the Spectroscopy ORiented Configuration Interaction (SORCI), the approximate linear-response coupled-cluster method of second order (CC2) and the algebraic-diagrammatic-construction scheme of the polarization propagator of second and third orders (ADC(2) and ADC(3)).

More information coming soon.