the one-dimensional model of lippincott and schroeder for hydrogen bond has been re-examined and it has been shown that o-h bond distance depends on repulsive van der waals and attractive electrostatic potentials.it has been shown that constant b in the van der waals repulsion potential is not transferable to all hydrogen bonds. the possibility of obtaining the semi-empircal parameters in the l...

Quantum chemical calculations of CF(3)Br and the CF(3) radical are performed using density functional theory (DFT) and time-dependent DFT (TDDFT). Molecular structures, vibrational frequencies, dipole moment, bond dissociation energy, and vertical excitation energies of CF(3)Br are calculated and compared with available experimental results. The performance of six hybrid and five hybrid meta fu...

To gain an atomistic-level understanding on physical and chemical processes occurring at the interfaces of hypergolic propellants, we carried out the first reactive dynamic (ReaxFF) simulations to study the reactive hypergolic mixture of monomethylhydrazine (MMH) and dinitrogen tetroxide (NTO), in comparison with the ethanol (EtOH) and NTO mixture that is reactive but nonhypergolic. Our studies...

In this response to the preceding paper by Bader, we show that the core arguments and statements presented in the latter are flawed. We argue that it is insufficient for a model of the chemical bond to be rooted in quantum mechanics. A good model must in addition provide insight and possess predictive power. Our molecular orbital (MO) model of the chemical bond, in particular, the associated en...

It has been argued that cellphones are safe because a single microwave photon does not have enough energy to break a chemical bond. We show that cellphone technology operates in the classical wave limit, not the single photon limit. Based on energy densities relative to thermal energy, we estimate thresholds at which effects could be possible. These seem to correspond somewhat with many experim...

It is well established that the hydrogen bond plays crucial role in many areas of physical, chemical and biological phenomena. The relevant proton transfer reactions are the simplest but very important in many chemical problems as well as in some biological processes. It appears that the low-barrier hydrogen bond (LBHB) for this displacement may play fundamental role in stabilizing intermediate...

Peptides are flexible The experimental parameters measured in n.m.r. studies, such as nuclear Overhauser effects (NOEs), coupling constants and chemical shifts, are all time averaged [ 11. NOEs are averaged by any process occurring faster than the cross-relaxation rate [2], which is usually in the range 0.1-50 s-'. Coupling constants are averaged by processes that occur faster than the coupling...