Nonresonant inelastic electron and X-ray scattering cross sections for bound-to-bound transitions in atoms and molecules are calculated directly from ab initio electronic wavefunctions. The approach exploits analytical integrals of Gaussian-type functions over the scattering operator, which leads to accurate and efficient calculations. The results are validated by comparison to analytical cross...

This article addresses a fundamental problem faced by the ab initio community: the lack of an effective formalism for the rapid exploration and exchange of new methods. To rectify this, we introduce a novel, basis-set independent, matrix-based formulation of generalized density functional theories which reduces the development, implementation, and dissemination of new ab initio techniques to th...

Molecular constants have been computed for the ground states 2∏ of 17OH and 1Σ of 107AgH+. The valence-bond method and advanced computational technique were used to perform all-electron ab initio calculation of molecular electronic structures. The basic idea behind the model is to introduce the molecular wave functions in terms of Hartree-Fock many-electron atomic determinants. Full configurati...

The Hoyle state plays a crucial role in the helium burning of stars heavier than our Sun and in the production of carbon and other elements necessary for life. This excited state of the carbon-12 nucleus was postulated by Hoyle as a necessary ingredient for the fusion of three alpha particles to produce carbon at stellar temperatures. Although the Hoyle state was seen experimentally more than a...

This article addresses a fundamental problem faced by the ab initio community: the lack of an effective formalism for the rapid exploration and exchange of new methods. To rectify this, we introduce a novel, basis-set independent, matrix-based formulation of generalized density functional theories which reduces the development, implementation, and dissemination of new ab initio techniques to th...

The Direct Fusion Drive (DFD) and its terrestrial counterpart, the Princeton Field Reversed Configuration Reactor, have seen significant developments in past decade. Various groups conducted detailed research on required specifications of engine associated technology for power delivery to onboard avionics payloads. Multiple studies also addressed thrust generation mechanism using empirical spec...

The diffusion of hydrogen in aluminum is thought to be a critical process in the embrittlement of aluminum. Experimentally determined diffusivities reported in the literature, however, provide little guidance into understanding hydrogen diffusion in aluminum as measurements taken at 20 C vary by over 17 orders of magnitude. Herein, we use ab initio methods to elucidate the elementary diffusion ...

the potential energy surface pes of (h2)2 dimer has been investigated, using five simple rigid rotor models. these models are called: head to head, symmetric side to side, l , steplike and t model. all calculations were done at two levels of ab initio  methods: mp2(full) and qcisd (t,full) using cc-pvtz basis set at singlet state of spin multiplicity. the results of scanning pes were then fitte...