A comprehensive investigation of the (1)pi pi*, (1)n pi* and (1)pi sigma* excited states of xanthine has been performed with the CASSCF, CASPT2, CC2 and ADC(2) methods. The 7H-diketo and 9H-diketo tautomers of xanthine, which are the lowest-energy tautomers in the ground state, have been studied. Out-of-plane deformation of the purine system in the lowest (1)pi pi* state as well as dissociation...

1,1-difluoroethylene (1,1-C2H2F2) molecules have been studied for the first time experimentally and theoretically by electron and positron impact. 0.4-1000 eV electron and 0.2-1000 eV positron impact total cross sections (TCSs) were measured using a retarding potential time-of-flight apparatus. In order to probe the resonances observed in the electron TCSs, a crossed-beam method was used to inv...

Background: Understanding of the incident electron energy and angular distributions from clinical electron accelerators (linacs) is important for dosimetry and treatment planning. The most important goals of this study were to evaluate the energy fluence and angular distributions of electron beams from a Neptun 10PC linac using the Monte Carlo (MC) code. Materials and Methods: The lina...

Plants respond adaptively to orthophosphate (Pi) deprivation through the induction of alternative pathways of glycolysis and mitochondrial electron transport. These respiratory bypasses allow respiration to proceed in Pi-deficient plant cells because they negate the necessity for adenylates and Pi, both pools of which are severely depressed following nutritional Pi starvation.

A fast method is developed for calculating the random phase approximation (RPA) correlation energy for density functional theory. The correlation energy is given by a trace over a projected RPA response matrix, and the trace is taken by a stochastic approach using random perturbation vectors. For a fixed statistical error in the total energy per electron, the method scales, at most, quadratical...

The DNA molecule has properties that allow it to act as a quantum logic processor. It has been demonstrated that there is coherent conduction of electrons longitudinally along the DNA molecule through pi stacking interactions of the aromatic nucleotide bases, and it has also been demonstrated that electrons moving longitudinally along the DNA molecule are subject to a very efficient electron sp...