Locating conical intersections relevant to photochemical reactions

  title={Locating conical intersections relevant to photochemical reactions},
  author={Bernhard Dick and Yehuda Haas and Shmuel Zilberg},
  journal={Chemical Physics},
17 Citations
Systematic exploration of minimum energy conical intersection structures near the Franck-Condon region.
The present approach combines the seam model function approach with the recently proposed single-component artificial force induced reaction method to find MECIs systematically, and requires neither a Hessian nor a derivative coupling vector.
Conical Intersections Leading to Chemical Reactions in the Gas and Liquid Phases
The current status of the role of conical intersections (CoIns) in molecular photochemistry is reviewed with a special emphasis on the procedures used to locate them. Due to space limitations, the
Photoreactivity of a push-pull merocyanine in static electric fields: a three-state model of isomerization reactions involving conical intersections.
It is shown that applying an external electric field or varying the solvent polarity changes the relative energies of the different transition states as well as that of the conical intersection, and thus different photochemical products can be obtained.
Description of Conical Intersections with Density Functional Methods.
It is demonstrated that the commonly used linear-response time-dependent theory does not yield a proper description of conical intersections and the potential energy surfaces in their vicinity and that one should instead use alternative computational approaches.
Assessment of approximate computational methods for conical intersections and branching plane vectors in organic molecules.
Comparisons support the use of the tested quantum-chemical methods for modeling the photochemistry of large organic and biological systems by demonstrating reasonable agreement in the computed relative energies.
Gradient Projection Method for Constraint Optimization and Relaxed Energy Paths on Conical Intersection Spaces and Potential Energy Surfaces.
  • B. Dick
  • Physics
    Journal of chemical theory and computation
  • 2009
A gradient projection algorithm is presented that permits the application of several constraints during geometry optimization on electronic potential energy surfaces (PES) or conical intersection (CI) seams and determines relaxed energy paths (REP) without the need to assign an internal coordinate as the reaction coordinate.
Photoexcited conversion of gauche-1,3-butadiene to bicyclobutane via a conical intersection: energies and reduced density matrices from the anti-Hermitian contracted Schrödinger equation.
The ACSE, MCSCF, and second-order multi-reference many-body perturbation theory (MRPT2) all demonstrate that there exists a family of pathways from gauche-1,3-butadiene to bicyclobutane via a conical intersection that are monotonically decreasing in energy, confirming a conjecture by Sicilia et al.
Automated Search for Minimum Energy Conical Intersection Geometries between the Lowest Two Singlet States S0/S1-MECIs by the Spin-Flip TDDFT Method.
The present hybrid method of SMF/ADDF and SF-TDDFT is shown to be a promising approach to locate S0/S1-MECIs of large systems automatically with modest computational costs.


The use of elementary reaction coordinates in the search for conical intersections
A method to locate conical intersections between the ground-state potential surface and the first electronically excited states of polyatomic molecules is described. It is an extension of the
Conical intersections in H2Cl+(1A')
A 10×10 model Hamiltonian matrix for the 1A’ states of the H2Cl+ molecule in a valence‐bond basis is shown to exhibit conical intersections between states 2 and 3 along a line in configuration space
Charge-transfer effects in the gas-phase protonation of ozone: Locating the conical intersections
We have performed fully correlated calculations using as a basis set the cc-pV5Z expansion with geometry optimization for the O3H+ moiety and have then calculated the partial cuts of the potential
Conical intersections in thymine.
The mechanisms which are responsible for the radiationless deactivation of the npi* and pipi* excited singlet states of thymine have been investigated, and the lowest-energy conical intersection (CI1) arises from a crossing of the lowest 1pipi* state with the electronic ground state, explaining the experimental observation of a long-lived population of dark excited states in gas-phase thymine.
Quadratic description of conical intersections: characterization of critical points on the extended seam.
This paper presents a practical approach for the characterization of critical points on conical intersection seams as either local minima or saddle points using second-derivative technology and illustrates the latter idea for the cyclopentadienyl radical.
A conical intersection mechanism for the photochemistry of butadiene. A MC-SCF study
The excited state (2 1 Ag) reaction paths involved in the photochemical transformations of butadiene have been studied via ab initio MC-SCF methods. It is demonstrated that the reaction funnel
Optimization of Conical Intersections with Floating Occupation Semiempirical Configuration Interaction Wave Functions
We outline a new implementation of a minimal energy conical intersection (MECI) optimization algorithm within the context of semiempirical methods. Computationally, this semiempirical conical
Locating Electronic Degeneracies of Polyatomic Molecules: A General Method for Nonsymmetric Molecules
A general method for finding all electronic degeneracies lying on the ground-state potential surface of a molecular system is proposed. The method is based on the idea that the spin pairing of the