Professor and Chair of Chemistry, Imperial College, London (U.K.)
Ph. D., University of Toronto
D. Sc., University of London
Contributions to Gaussian: CASSCF Methods
Dr. Robb’s current research includes both methods development and applications studies, focusing on Multi-Configuration SCF methods (MC-SCF), which is also known as the Complete Active Space SCF (CASSCF) method. These calculations combine an SCF calculation with a full Configuration Interaction computation involving a subset of the molecular orbitals known as the active space. The CASSCF method has many uses and is especially suited to the study of excited states.
CASSCF code developed by Dr. Robb and his colleagues first appeared in Gaussian 90. Current CASSCF capabilities include coupled perturbed CASSCF as well as a direct CASSCF algorithm. Algorithmic improvements increase the maximum practical size for an active space to 14 orbitals. These features include:
- RASSCF (multi reference CI) is also available.
- MP2 correlation may optionally be included in CASSCF calculations (include both the CASSCF and MP2 keywords in the job’s route section).
- Conical intersections may be predicted (Opt=Conical).
- Approx. spin orbit coupling between two spin states can be computed.
Dr. Robb’s applications research centers on theoretical studies of photochemical mechanisms. Recent work involves coupling electronic structure computations with direct quantum dynamics. This has involved collaboration with Graham Worth (Birmingham), Benjamin Lasorne (Montpéllier) and Artur Izmaylof (Toronto).
- M. A. Robb, Theoretical Chemistry for Electronic Excited States, Royal Society of Chemistry, 2018.
- M. Vacher, M. J. Bearpark, M. A. Robb, J. P. Malhado. “Electron Dynamics upon Ionization of Polyatomic Molecules: Coupling to Quantum Nuclear Motion and Decoherence”, Phys. Rev. Lett. 118 (2017) 083001.
- M. Vacher, M. J. Bearpark, M. A. Robb, “Direct methods for non-adiabatic dynamics: connecting the single-set variational multi-configuration Gaussian (vMCG) and Ehrenfest perspectives”, Theor. Chem. Acc. 135: 187 (2016).
- J. Meisner, M. Vacher, M.J. Bearpark, M. A. Robb, “Geometric Rotation of the Nuclear Gradient at a Conical Intersection: Extension to Complex Rotation of Diabatic States”, J. Chem. Theor. Comp. 11 (2015) 3115.
- M. A. Robb, “In This Molecule There Must Be a Conical Intersection.”, In Williams, I. H.and Williams, N. H., eds., Advances in Physical Organic Chemistry 48, Elsevier Ltd.: Academic Press, 2014, 189–228.
- S. Ruiz-Barragan, M. A. Robb, L. Blancafort, “Conical Intersection Optimization Based on a Double Newton-Raphson Algorithm Using Composed Steps”, J. Chem. Theor. Comp. 9 (2013) 1433-1442.
- L. Blancafort and M. A. Robb, “A Valence Bond Description of the Pre-fulvene Extended Conical Intersection Seam of Benzene”, J. Chem. Theor. Comp. 8 (2012) 4922-4930.
- A. F. Izmaylov, D Mendive–Tapia, M. J. Bearpark, M. A. Robb, J. C. Tully, Michael J. Frisch, “Nonequilibrium Fermi golden rule for electronic transitions through conical intersections”, J. Chem. Phys. 135 (2011) 234106.
- A. Nenov, P. Kölle, M. A. Robb, R de Vivie-Riedle, “Beyond the van der Lugt / Oosterhoff model: When the Conical Intersection Seam and the S1 Minimum Energy Path do not Cross”, J. Org. Chem. 75 (2010) 123-129.
- C.S. Allan, B. Lasorne, G.A. Worth, M.A. Robb, “A Straightforward Method of Analysis for Direct Quantum Dynamics: Application to the Photochemistry of a Model Cyanine dye”, J. Phys. Chem. A 114 (2010) 8173-8729.
- F Sicilia, L Blancafort, M J. Bearpark, and M A. Robb, “New Algorithms for Optimizing and Linking Conical Intersection Points”, J. Chem. Theor. Comput. 4 (2008) 257-266.
- S. Vanni, M. Garavelli and M. A. Robb, “A New Formulation of the Phase Change Approach in the Theory of Conical Intersections” Chem. Phys. 347 (2008) 46-56.
- G. Groenhof, L. V. Schäfer, M Boggio-Pasqua, H Grubmüller, M. A. Robb, “Arginine52 controls the photoisomerization process in Photoactive Yellow Protein”, J. Amer. Chem. Soc. 130 (2008) 3250.
- Araujo, M.; Lasorne, B.; Bearpark, M. J.; Robb, “The Photochemistry of Formaldehyde: Internal Conversion and Molecular Dissociation in a Single Step?”, J. Phys. Chem. A 112 (2008) 7489-7491.
- Lasorne, B.; Bearpark, M. J.; Robb, M. A.; Worth, G. A., “Controlling S1/S0 Decay and the Balance between Photochemistry and Photostability in Benzene: A Direct Quantum Dynamics Study”, J. Phys. Chem. A (the Sason Shaik Festschrift) 112 (2008) 13017-13027.
Last update: 10 February 2023