Quantum fidelity susceptibility in excited state quantum phase transitions: application to the bending spectra of nonrigid molecules

We characterize excited state quantum phase transitions in the two dimensional limit of the vibron model with the quantum fidelity susceptibility, comparing the obtained results with the information provided by the participation ratio. As an application, we locate the eigenstate closest to the barrier to linearity and determine the linear or bent character of the different overtones for particular bending modes of six molecular species. We perform a fit and use the optimized eigenvalues and eigenstates in three cases and make use of recently published results for the other three cases.

Gas-phase high-resolution molecular spectroscopy for LAV molecules

High-resolution infrared (IR) spectroscopy is essential to the analysis of molecular rotation-vibration spectra. The high-resolution spectra deliver much information about structure and dynamic of molecules, but often they are very complex. For nonrigid molecules the complexity arises from transition tunneling splittings. Methylamine is a classic example of a nonrigid molecule in which two large amplitude motions, inversion and torsion, occur simultaneously. It has six equivalent potential minima, for which an effective vibration-inversion-torsion-rotation Hamiltonian has been developed. In the chapter assignment and analysis of several spectral regions of methylamine have been briefly presented explaining the assigning techniques and theoretical treatment of experimental lines.

A formal approach to the molecular fuzzy lock-and-key

The fuzzy lock-and-key (FLK) powers a vast array of sophisticated logic gates at inter- and intra-cellular levels. We invoke representations of groupoid tiling wreath products analogous to the study of nonrigid molecules - or of related fuzzy symmetry extensions - to build a Morse Function that can describe spontaneous symmetry breaking phase transitions driven by information catalysis. The Function can, however, also be used to construct an Onsager-like stochastic dynamics, linked to the phase transition approach by the rich stability criteria associated with stochastic differential equations. The two methods provide complementary ways of looking at the FLK. A limit condition emerging from the stochastic dynamics gives insight into a cellular 'generalized inflammation' requiring progressively higher commitment of metabolic free energy for maintenance of basic FLK processes. These results suggest that more systematic study may illuminate pathologies associated with the failure of the FLK, a centrally-important but enigmatic biological process.

A formal approach to the molecular fuzzy lock-and-key

The fuzzy lock-and-key (FLK) powers a vast array of sophisticated logic gates at inter- and intra-cellular levels. We invoke representations of groupoid tiling wreath products analogous to the study of nonrigid molecules - or of related fuzzy symmetry extensions - to build a Morse Function that can describe spontaneous symmetry breaking phase transitions driven by information catalysis. The Function can, however, also be used to construct an Onsager-like stochastic dynamics, linked to the phase transition approach by the rich stability criteria associated with stochastic differential equations. The two methods provide complementary ways of looking at the FLK. A limit condition emerging from the stochastic dynamics gives insight into a cellular 'generalized inflammation' requiring progressively higher commitment of metabolic free energy for maintenance of basic FLK processes. These results suggest that more systematic study may illuminate pathologies associated with the failure of the FLK, a centrally-important but enigmatic biological process.