Do you have a method you would like to use for studying photochemical reaction paths? Did you develop a new electronic structure method that you would like to test in different regions of a potential energy surface, including near-crossing regions? Are you interested in biological organic chromophores ? If so, you may be interested in testing your method on our Benchmark potential energy scans provided below.

The Project was developed in our group within the activities of the IUPAC Subcommittee on Photochemistry and involved the contribution of the groups of:

Celestino Angeli

Nicolas Ferrè

Michael Filatov

Alexander Granovsky

Miquel Huix-Rotllant

Roland Lindh

Anna Krylov

Donald Truhlar

Our group has produced a series of benchmark studies employing a reduced model of retinal protonated Schiff base (rPSB), the chromophore of visual pigments. This model, the Penta-2,4-dieniminium or 2,4-Pentadienylideneamonium cation (PSB3) features 3 double bonds but still preserves many of the features of the ground (S0) and first excited state (S1) potential energy surfaces of rPSB.

The benchmarks consist of a series of geometries tracing important pathways on the S0 and S1 surfaces of PSB3. These pathways follow reaction coordinates involved in the thermal and photochemical reactions of PSB3. More importantly, they pass through regions with different/changing electronic structure, and therefore provide a stringent test for electronic structure methods’ ability to describe these different pathways correctly. For more information, see the following references:

1.Gozem, S.; Huntress, M.; Schapiro, I.; Lindh, R.; Granovsky, A.A.; Angeli, C.; Olivucci, M. Dynamic Electron Correlation Effects on the Ground State Potential Energy Surface of a Retinal Chromophore Model. J. Chem. Theory Comput. 2012, 8, 4069-4080. 

2.Gozem, S.; Melaccio, F.; Lindh, R.; Krylov, A.I.; Granovsky, A.A.; Angeli, C.; Olivucci, M. Mapping the excited state potential energy surface of a retinal chromophore model with multireference and EOM-CC methods. J. Chem. Theory Comput. 2013, 9, 4495-4506.

3.Gozem, S.; Krylov, A.I.; Olivucci, M. Conical Intersection and Potential Energy Surface Features of a Model Retinal Chromophore: Comparison of EOM-CC and Multireference Methods. J. Chem. Theory Comput. 2013, 9, 284-292.

4.Xu, X.; Gozem, S.; Olivucci, M.; Truhlar, D. Combined Self-Consistent-Field and Spin-Flip Tamm Dancoff Density Functional Approach to Potential Energy Surfaces for Photochemistry. J. Phys. Chem. Lett. 2013, 4, 253-258.

5.Huix-Rotllant, M.; Filatov, M.; Gozem, S.; Schapiro, I.; Olivucci, M.; Ferré, N. Assessment of density functional theory for describing the correlation effects on the ground and excited state potential energy surfaces of a retinal chromophore model. J. Chem. Theory Comput. 2013, 9, 3917-3932.

6.Gozem, S. Melaccio, F., Valentini, A., Filatov, M., Huix-Rotllant, M., Ferre, N., Frutos, L. M., Angeli, C., Krylov, A.I., Granovsky, A. A., Lindh, R., Olivucci, M. Shape of Multireference, Equation-of-Motion Coupled-Cluster, and Density Functional Theory Potential Energy Surfaces at a Conical Intersection, J. Chem. Theory Comput., 2014, 10, 3074–3084.

These pathways have been used to test Multiconfigurational/Multireference methods (see refs. 1 and 2), Equation-of-motion coupled cluster methods (refs. 2 and 3), and Density functional theory methods (refs. 4 and 5). The potential energy surfaces obtained with these methods are compared to those obtained at the highest level of theory, MRCISD+Q. Under testing are QMC (with Leonardo Guidoni) methods and CC2 methods (with Tadeusz Andruniow)

Here we provide the structures used in these benchmark studies. The paths themselves are minimum energy paths or interpolations/extrapolations of coordinates, which were either obtained at the CASSCF/6-31G* level of theory or CASPT2(IPEA=0.25)/6-31G* level of theory.

From ref. 1:
cis-PSB3 geometry (reference)        CASSCF                

trans-PSB3 geometry                       CASSCF                      

BLA Scan geometries                       CASSCF                      

MEPCT Scan geometries                 CASSCF                      

MEPDIR Scan geometries                CASSCF

Table of Energies (Excel file)            CASSCF
trans-PSB3 geometry (reference)                                      CASSCF                              CASPT2

MEPCIS (cis-PSB3 to CICIS) geometries                          CASSCF                              CASPT2

CI Seam (CICIS to CITRANS) geometries                         CASSCF                              CASPT2

MEPTRANS (CITRANS to trans-PSB3) geometries          CASSCF                              CASPT2

Table of Energies (Excel file)                                              CASSCF                              CASPT2
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Dipartmento di Chimica

Universita di Siena

Via A. De GasPeri 2, 53100 Siena, Italy
Prof. Massimo Olivucci