This article presents a multifaceted study of the reaction H+C(2)H(6)-->H(2)+C(2)H(5) and three of its deuterium-substituted isotopologs. First we present high-level electronic structure calculations by the W1, G3SX, MCG3-MPWB, CBS-APNO, and MC-QCISD/3 methods that lead to a best estimate of the barrier height of 11.8+/-0.5 kcal/mol. Then we obtain a specific reaction parameter for the MPW dens...

Quantum statistical mechanics is statistical mechanics applied to quantum mechanical systems. In quantum mechanics a statistical ensemble (probability distribution over possiblequantum states) is described by a density operatorS, which is a nonnegative, self-adjoint, trace-classoperator of trace 1 on the Hilbert space Hdescribing the quantum system. This can be shown under various mathematical ...

We generalize the ZX calculus to quantum systems of dimension higher than two. The resulting calculus is sound and universal for quantum mechanics. We define the notion of a mutually unbiased qudit theory and study two particular instances of these theories in detail: qudit stabilizer quantum mechanics and Spekkens-Schreiber toy theory for dits. The calculus allows us to analyze the structure o...

Some of the articles address the difficulties students have learning particular aspects of quantum mechanics. Others describe different interpretations, formulations, and representations in quantum mechanics. Still others discuss novel applications or some of the more subtle conceptual issues in quantum mechanics. A few of the articles address the integration of workable and affordable quantum ...

Benchmark calculations of proton affinities and gas-phase basicities of molecules most relevant to biological phosphoryl transfer reactions are presented and compared with available experimental results. The accuracy of proton affinity and gas-phase basicity results obtained from several multi-level model chemistries (CBS-QB3, G3B3, and G3MP2B3) and density-functional quantum models (PBE0, B1B9...

Bohmian mechanics is a theory of quantum phenomena based on a particle picture. On a fundamental level, it explains the world around us in terms of point particles that move on deterministic paths. When used to describe experimental situations, Bohmian mechanics yields the textbook formalism of quantum mechanics, and can therefore be considered as an explanation of the axioms of standard quantu...

Conformations and electronic properties of a series of imidazobenzodiazepines are investigated by AM1 semi-empirical quantum mechanics method. It is shown that substitution of Cl in position 7 instead of 8, changes the geometry of the seven membered lactam ring; this may put the N5 nitrogen in a better positon to act as a hydrogen bond acceptor, and the phenyl ring in position 6 is probably...