György Lendvay

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Theoretical model calculations were performed to investigate the degree of validity of the mobile proton model of protonated peptides. The structures and energies of the most important minima corresponding to different structural isomers of protonated diglycine and their conformers, as well as the barriers separating them, were determined by DFT(More)
The mobile proton model was critically evaluated by using purely theoretical models which include quantum mechanical calculations to determine stationary points on the potential energy surface (PES) of a model compound, and Rice-Ramsperger-Kassel-Marcus (RRKM) calculations to determine the rate constants of various processes (conformational changes, proton(More)
Theoretical model calculations were performed to validate the 'mobile proton' model for protonated lysylglycine (KG). Detailed scans carried out at various quantum chemical levels of the potential energy surface (PES) of protonated KG resulted in a large number of minima belonging to various protonation sites and conformers. Transition structures(More)
The mechanism of the formation of a2+ ions from b2+ ions occurring during fragmentation of protonated peptides is investigated using quantum chemical methods. The geometries of the stationary structures involved in two possible mechanisms, namely, a two-step mechanism via an open-chain acylium ion and a concerted pathway involving rupture of two covalent(More)
We use the fewest switches nonadiabatic trajectory surface hopping approach to study the photodissociation of methane on its lowest singlet excited state potential surface (1 (1)T(2)) at 122 nm, with emphasis on product state branching and energy partitioning. The trajectories and couplings are based on CASSCF(8,9) calculations with an aug-cc-pvdz basis(More)
Density functional theoretical methods, including several basis sets and two functional, were used to collect information on the structure and energetic parameters of poly(ethylene glycol) (PEG), also referred to as poly(ethylene oxide) (PEO), coordinated by alkali metal ions. The oligomer chain is found to form a spiral around the alkali cation, which(More)
Converged differential and integral cross sections are reported for the H + O2 --> OH + O reaction on an improved potential energy surface of HO2(X2A'') using a dynamically exact quantum wave packet method and Gaussian weighted quasi-classical trajectory method. The complex-forming mechanism is confirmed by strong forward and backward scattering peaks and(More)
Two global analytical potential energy surfaces for the HO2(X2A") system have been developed by fitting approximately 15,000 ab initio points at the icMRCI+Qaug-cc-pVQZ level of theory, using the reproducing kernel Hilbert space method. One analytical potential is designed to give a very accurate representation of the low energy range that determines the(More)