Assessing computationally efficient isomerization dynamics: ΔSCF density-functional theory study of azobenzene molecular switching
Abstract
We present a detailed comparison of the S0, S1 (n → π*) and S2 (π → π*) potential energy surfaces (PESs) of the prototypical molecular switch azobenzene as obtained by Δ-self-consistent-field (ΔSCF) density-functional theory (DFT), time-dependent DFT (TD-DFT) and approximate coupled cluster singles and doubles (RI-CC2). All three methods unanimously agree in terms of the PES topologies, which are furthermore fully consistent with existing experimental data concerning the photo-isomerization mechanism. In particular, sum-method corrected ΔSCF and TD-DFT yield very similar results for S1 and S2, when based on the same ground-state exchange-correlation (xc) functional. While these techniques yield the correct PES topology already on the level of semi-local xc functionals, reliable absolute excitation energies as compared to RI-CC2 or experiment require an xc treatment on the level of long-range corrected hybrids. Nevertheless, particularly the robustness of ΔSCF with respect to state crossings as well as its numerical efficiency suggest this approach as a promising route to dynamical studies of larger azobenzene-containing systems.
- Publication:
-
Journal of Chemical Physics
- Pub Date:
- December 2011
- DOI:
- 10.1063/1.3664305
- arXiv:
- arXiv:1202.4671
- Bibcode:
- 2011JChPh.135v4303M
- Keywords:
-
- coupled cluster calculations;
- density functional theory;
- electron correlations;
- exchange interactions (electron);
- excited states;
- ground states;
- isomerisation;
- molecular configurations;
- molecule-photon collisions;
- organic compounds;
- photochemistry;
- potential energy surfaces;
- SCF calculations;
- 31.15.eg;
- 31.15.xr;
- 31.15.bw;
- 31.50.Bc;
- 31.50.Df;
- 82.30.Qt;
- Exchange-correlation functionals;
- Self-consistent-field methods;
- Clusters: electronic properties equilibrium geometries coupled-cluster theory;
- Potential energy surfaces for ground electronic states;
- Potential energy surfaces for excited electronic states;
- Isomerization and rearrangement;
- Physics - Chemical Physics;
- Condensed Matter - Materials Science
- E-Print:
- 25 pages, 6 figures