Three Dimensional Potential Energy Surface For The F3

In order to study the F3 system, an accurate global adiabatic potential energy surface is reduced in the present work. The high level ab initio (MCSCF/MRCI level) methods with big basis set aVQZ are used to calculate 27690 potential energy points in MOLPRO quantum chemistry package using Jacobi coordinate. Meanwhile, B-spline fit method is used to reduce the global potential energy surface in this present work. The shallow well complexes are found in the present work when the angles θ = 30°, 60°, and 90°. Analysing the global potential energy surfaces one can get the conclusion that reactants should overcome at least 0.894 eV energy to cross transition state and reach products.

The Jahn–Teller and Pseudo-Jahn–Teller Effects: A Unique and Only Source of Spontaneous Symmetry Breaking in Atomic Matter

In a mostly review paper, we show that the important problem of symmetry, broken symmetry, and spontaneous broken symmetry of polyatomic systems is directly related to the Jahn–Teller (JT) and pseudo-Jahn–Teller (PJT) effects, including the hidden-JT and hidden-PJT effects, and these JT effects (JTEs) are the only source of spontaneous symmetry breaking in matter. They are directly related to the violation of the adiabatic approximation by the vibronic and other nonadiabatic couplings (jointly termed nonadiabaticity) in the interaction between the electrons and nuclei, which becomes significant in the presence of two or more degenerate or pseudodegenerate electronic states. In a generalization of this understanding of symmetry, we suggest an improved (quantum) definition of stereo-chemical polyatomic space configuration, in which, starting with their high-symmetry configuration, we separate all atomic systems into three distinguishable groups: (1) weak nonadiabaticity, stable high-symmetry configurations; (2) moderate-to-strong nonadiabaticity, unstable high-symmetry configurations, JTEs, spontaneous symmetry breaking (SSB); (3) very strong nonadiabaticity, stable distorted configurations. The JTEs, inherent to the second group of systems, produce a rich variety of novel properties, based on their multiminimum adiabatic potential energy surface (APES), leading to a short lifetime in the distorted configuration. We show the role of the Curie principle in the possibilities to observe the SSB in atomic matter, and mention briefly the revealed recently gamma of novel properties of matter in its interaction with external perturbation that occur due to the SSB, including ferroelectricity and orientational polarization, leading to enhanced permittivity and flexoelectricity.

Pseudo Jahn–Teller origin of twisting in 3,6-pyridazinedione derivatives; N2C4H2Y2Z2 (Y = O, S, Se, Z = H, F, Cl, Br) compounds

3,6-pyridazinedione and two of its derivatives where oxygen atoms of the molecule are substituted by two sulfur or selenium ( N 2 C 4 Y 2 H 4) were studied with the goal of answering the following question: "Which N 2 C 4 Y 2 H 4 compounds are unstable in their planar configuration?" Additionally, the origin of the twisting instability of 3,6-pyridazinedione planar configuration and three of its 1,2-dihalo derivatives ( N 2 C 4 H 2 O 2 Z 2) were rationalized by employing the pseudo Jahn–Teller effect (PJTE) to explain the difference between N 2 C 4 H 2 O 2 Z 2 structures in series. Therefore, the structures of six 3,6-pyridazinediones ( N 2 C 4 H 2 Y 2 Z 2) were optimized in both equilibrium and planar configurations, and their vibrational frequencies were calculated. Then the adiabatic potential energy surface (APES) profiles along the a2 distortion coordinates were calculated. Based on the calculation results, N 2 C 4 S 2 H 4 and N 2 C 4 Se 2 H 4 compounds were stable in the planar structure; but, due to the vibronic coupling interaction between the 1A1 ground state and the first excited state 1A2, the twisting instability occurred in planar N 2 C 4 H 2 O 2 Z 2 series. The (1 A 1 + 1 A 2) ⊗ a2 problem was found to be the reason of the breaking symmetry phenomena in all the four N 2 C 4 H 2 O 2 Z 2 in series from unstable planar configuration (highest-symmetry C 2v ) to the stable twisted geometry with C 2 symmetry. Finally, the vibronic coupling constants of the PJTE of the compounds in series were estimated by fitting the secular equation roots along the normal coordinates of distortion.