Diabatic Molecular Orbitals, Potential Energies, and Potential Energy Surface Couplings by the 4-fold Way for Photodissociation of Phenol.

Complete-active-space self-consistent-field (CASSCF) calculations provide useful reference wave functions for configuration interaction or perturbation theory calculations of excited-state potential energy surfaces including dynamical electron correlation. However, the canonical molecular orbitals (MOs) of CASSCF calculations usually have mixed character in regions of strong interaction of two or more electronic states; therefore, they are unsuitable for diabatization using the configurational uniformity approach. Here, CASSCF diabatic MOs for phenol have been obtained by the 4-fold way, and comparison to the CASSCF canonical MOs shows that they are much smoother. Using these smooth CASSCF diabatic MOs, we performed direct diabatization calculations for the three low-lying states ((1)ππ, (1)ππ*, and (1)πσ*) and their diabatic (scalar) couplings at the dynamically correlated multiconfiguration quasidegenerate perturbation theory (MC-QDPT) level. We present calculations along the O-H stretching and C-C-O-H torsion coordinates for the nonadiabatic photodissociation of phenol to the phenoxyl radical and hydrogen atom. The seams of (1)ππ*/(1)πσ* and (1)ππ/(1)πσ* diabatic crossings are plotted as functions of these coordinates. We also present diabatization calculations for displacements along the out-of-plane ring distortion modes 16a and 16b of the phenyl group. The dominant coupling modes of the two conical intersections ((1)ππ*/(1)πσ* and (1)ππ/(1)πσ*) are discussed. The present diabatization method is confirmed to be valid even for significantly distorted ring structures by diabatization calculations along a reaction path connecting the planar equilibrium geometry of phenol to its strongly distorted prefulvenic form. The present work provides insight into the mode specificity of phenol photodissociation and shows that diabatization at the MC-QDPT level employing CASSCF diabatic MOs can be a good starting point for multidimensional dynamics calculations of photochemical reactions.

[1]  W. Lichten.  Resonant Charge Exchange in Atomic Collisions , 1963 .

[2]  H. D. Bist,et al.  The 2750-Å electronic band system of phenol: Part I. The in-plane vibrational spectrum , 1966 .

[3]  H. D. Bist,et al.  The vibrational spectrum and torsion of phenol , 1967 .

[4]  H. D. Bist,et al.  The 2750-Å band system of phenol: Part II. Extended vibrational assignments and band contour analysis , 1967 .

[5]  B. Ward.  Absorption spectra of aromatic free radicals: a vibrational analysis of the 3050 Å absorption spectrum of benzyl and a new transition of phenoxyl , 1968 .

[6]  Mixing of ionic and covalent configurations for sodium hydride, potassium hydride, and hydromagnesium(1+). Potential energy curves and couplings between molecular states , 1975 .

[7]  M. Baer.  Adiabatic and diabatic representations for atom-molecule collisions: Treatment of the collinear arrangement , 1975 .

[8]  W. Lipscomb,et al.  The synchronous-transit method for determining reaction pathways and locating molecular transition states , 1977 .

[9]  J. Delos,et al.  Diabatic and adiabatic representations for atomic collision processes , 1979 .

[10]  B. Roos,et al.  A complete active space SCF method (CASSCF) using a density matrix formulated super-CI approach , 1980 .

[11]  B. Roos,et al.  A Comparison of the Super-CI and the Newton-Raphson Scheme in the Complete Active Space SCF Method , 1980 .

[12]  M. Baer.  Electronic non-adiabatic transitions derivation of the general adiabatic-diabatic transformation matrix , 1980 .

[13]  Michael W. Schmidt,et al.  Are atoms intrinsic to molecular electronic wavefunctions? I. The FORS model , 1982 .

[14]  C. Mead,et al.  Conditions for the definition of a strictly diabatic electronic basis for molecular systems , 1982 .

[15]  B. C. Garrett,et al.  Derivative Coupling Elements in Electronically Adiabatic Representations and Their Use in Scattering Calculations , 1983 .

[16]  C. Mead,et al.  On the form of the adiabatic and diabatic representation and the validity of the adiabatic approximation for X3 Jahn–Teller systems , 1985 .

[17]  Philip J. M. Johnson,et al.  Radiationless transitions in gas phase phenol and the effects of hydrogen bonding , 1986 .

[18]  L. Cederbaum,et al.  Approximately diabatic states from block diagonalization of the electronic Hamiltonian , 1988 .

[19]  S. Colson,et al.  Deuterium isotope effects on S1 radiationless decay in phenol and on intermolecular vibrations in the phenol-water complex , 1989 .

[20]  T. H. Dunning.  Gaussian basis sets for use in correlated molecular calculations. I. The atoms boron through neon and hydrogen , 1989 .

[21]  T. Dunning,et al.  Electron affinities of the first‐row atoms revisited. Systematic basis sets and wave functions , 1992 .

[22]  Haruyuki Nakano,et al.  MCSCF reference quasidegenerate perturbation theory with Epstein—Nesbet partitioning , 1993 .

[23]  K. Ruedenberg,et al.  A quantum chemical determination of diabatic states , 1993 .

[24]  Haruyuki Nakano,et al.  Quasidegenerate perturbation theory with multiconfigurational self‐consistent‐field reference functions , 1993 .

[25]  K. Ruedenberg,et al.  Strong shifts in diabatic nondynamic electron correlations cause conical intersection between low‐lying closed‐shell adiabatic singlets of like symmetry in ozone , 1993 .

[26]  K. Ruedenberg,et al.  Determination of diabatic states through enforcement of configurational uniformity , 1997 .

[27]  J. Malrieu,et al.  On the quasidiabatic character of average natural orbitals , 1997 .

[28]  W. Domcke,et al.  Photoinduced Electron and Proton Transfer in Phenol and Its Clusters with Water and Ammonia , 2001 .

[29]  D. Truhlar,et al.  The direct calculation of diabatic states based on configurational uniformity , 2001 .

[30]  D. Truhlar,et al.  Direct diabatization of electronic states by the fourfold way. II. Dynamical correlation and rearrangement processes , 2002 .

[31]  Christophe Jouvet,et al.  Excited-state hydrogen detachment and hydrogen transfer driven by repulsive 1πσ* states: A new paradigm for nonradiative decay in aromatic biomolecules , 2002 .

[32]  Donald G. Truhlar,et al.  Properties of nonadiabatic couplings and the generalized Born–Oppenheimer approximation , 2002 .

[33]  Kimihiko Hirao,et al.  Intruder state avoidance multireference Møller–Plesset perturbation theory , 2002, J. Comput. Chem..

[34]  D. Truhlar,et al.  Extension of the fourfold way for calculation of global diabatic potential energy surfaces of complex, multiarrangement, non-Born–Oppenheimer systems: Application to HNCO(S0,S1) , 2003 .

[35]  C. Mead,et al.  Relative likelihood of encountering conical intersections and avoided intersections on the potential energy surfaces of polyatomic molecules , 2003 .

[36]  D. Truhlar,et al.  Introductory lecture: nonadiabatic effects in chemical dynamics. , 2004, Faraday discussions.

[37]  Z. Lan,et al.  Time-dependent quantum wave-packet description of the π1σ* photochemistry of phenol , 2005 .

[38]  M. Nix,et al.  The Role of πσ* Excited States in the Photodissociation of Heteroaromatic Molecules , 2006, Science.

[39]  M. A. Collins,et al.  Interpolation of multidimensional diabatic potential energy matrices. , 2006, The Journal of chemical physics.

[40]  M. Nix,et al.  High resolution photofragment translational spectroscopy studies of the near ultraviolet photolysis of imidazole. , 2006, The Journal of chemical physics.

[41]  D. Truhlar,et al.  Improved direct diabatization and coupled potential energy surfaces for the photodissociation of ammonia , 2007 .

[42]  O. Tapia,et al.  Generalized Electronic Diabatic Approach to Structural Similarity and the Hammond Postulate , 2007 .

[43]  Z. Lan,et al.  Ab initio characterization of the conical intersections involved in the photochemistry of phenol. , 2008, The Journal of chemical physics.

[44]  M. Nix,et al.  Exploring nuclear motion through conical intersections in the UV photodissociation of phenols and thiophenol , 2008, Proceedings of the National Academy of Sciences.

[45]  M. Nix,et al.  Observation of geometric phase effect induced photodissociation dynamics in phenol , 2008 .

[46]  D. Yarkony,et al.  Determining quasidiabatic coupled electronic state Hamiltonians using derivative couplings: A normal equations based method. , 2008, The Journal of chemical physics.

[47]  Rosendo Valero,et al.  Adiabatic states derived from a spin-coupled diabatic transformation: semiclassical trajectory study of photodissociation of HBr and the construction of potential curves for LiBr+. , 2008, The journal of physical chemistry. A.

[48]  J. Gauss,et al.  Quasidiabatic states described by coupled-cluster theory. , 2009, The Journal of chemical physics.

[49]  M. Nix,et al.  High resolution photofragment translational spectroscopy studies of the ultraviolet photolysis of phenol-d(5). , 2009, The journal of physical chemistry. A.

[50]  V. Stavros,et al.  Exploring the time-scales of H-atom detachment from photoexcited phenol-h(6) and phenol-d(5): statistical vs nonstatistical decay. , 2009, The journal of physical chemistry. A.

[51]  Conical intersections, charge localization, and photoisomerization pathway selection in a minimal model of a degenerate monomethine dye. , 2009, The Journal of chemical physics.

[52]  Hannah R. Leverentz,et al.  Efficient Diffuse Basis Sets: cc-pVxZ+ and maug-cc-pVxZ. , 2009, Journal of chemical theory and computation.

[53]  M. Fujii,et al.  Excited state hydrogen transfer dynamics in substituted phenols and their complexes with ammonia: ππ*-πσ* energy gap propensity and ortho-substitution effect. , 2010, The Journal of chemical physics.

[54]  Lee‐Ping Wang,et al.  The diabatic picture of electron transfer, reaction barriers, and molecular dynamics. , 2010, Annual review of physical chemistry.

[55]  Donald G Truhlar,et al.  Computational Thermochemistry: Scale Factor Databases and Scale Factors for Vibrational Frequencies Obtained from Electronic Model Chemistries. , 2010, Journal of chemical theory and computation.

[56]  D. Truhlar,et al.  Convergent Partially Augmented Basis Sets for Post-Hartree-Fock Calculations of Molecular Properties and Reaction Barrier Heights. , 2011, Journal of chemical theory and computation.

[57]  Joseph E. Subotnik,et al.  Diabatic couplings for charge recombination via Boys localization and spin-flip configuration interaction singles. , 2011, The Journal of chemical physics.

[58]  Sharon Hammes-Schiffer,et al.  Proton-coupled electron transfer versus hydrogen atom transfer: generation of charge-localized diabatic states. , 2011, The journal of physical chemistry. A.

[59]  K. Baeck,et al.  Quantum wave packet propagation study of the photochemistry of phenol: isotope effects (Ph-OD) and the direct excitation to the 1πσ* state. , 2011, The journal of physical chemistry. A.

[60]  M. Ashfold,et al.  Tunnelling under a conical intersection: application to the product vibrational state distributions in the UV photodissociation of phenols. , 2011, The Journal of chemical physics.

[61]  D. Truhlar,et al.  Photochemistry in a dense manifold of electronic states: photodissociation of CH2ClBr. , 2012, The Journal of chemical physics.

[62]  S. Bradforth,et al.  Contrasting the excited state reaction pathways of phenol and para-methylthiophenol in the gas and liquid phases. , 2012, Faraday discussions.

[63]  D. Truhlar,et al.  Direct diabatization of electronic states by the fourfold-way: Including dynamical correlation by multi-configuration quasidegenerate perturbation theory with complete active space self-consistent-field diabatic molecular orbitals , 2013 .