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Trapping Hydrogen Atoms From a Neon-Gas Matrix: A Theoretical Simulation

REA Auditado

Hydrogen is of critical importance in atomic and molecular physics and the development of a simple and efficient technique for trapping cold and ultracold hydrogen atoms would be a significant advance. In this study we simulate a recently proposed trap-loading mechanism for trapping hydrogen atoms released from a neon matrix. Accurate ab initio quantum calculations are reported of the neon-hydrogen interaction potential and the energy- and angular-dependent elastic scattering cross sections that control the energy transfer of initially cold atoms are obtained.

Tema: general: 

• Ciencias Sociales›Educación

A full-configuration interaction "nuclear orbital'' method to study doped 3He(N) clusters (N<=4)

REA Auditado

An efficient full configuration interaction (FCI) treatment, based on the Jacobi-Davidson algorithm, is developed in order to study small doped 3He(N) clusters. The state of each He atom in a given cluster is described by a set of wave-functions which by extention of the quantum-chemistry notation are caller here "nuclear orbitals". The FCI treatment is applied to the calculation of binding energies and helium natural orbitals of 3He(N) ... Br2(X) complexes. In agreement with our previous calculations using a Hartree-Fock approach [Phys. Rev. Lett.

Tema: general: 

• Ciencias

One-dimensional diffusion model in an Inhomogeneous region

REA Auditado

A one-dimensional model is developed to describe atomic diffusion in a graphite tube atomizer for electrothermal atomic adsorption spectrometry. The underlying idea of the model is the solution of an inhomogeneous one-dimensional diffusion equation, with the diffusion coefficient being a function of temperature over the entire inhomogeneous region. An analytical solution of the problem is obtained in the form of a Green’s function. http://www.springerlink.com/content/j817wt1070w53118/fulltext.pdf Copyright: 2006 Springer Verlag: This is the authors version of the work.

Tema: general: 

• Ciencias›Ciencias (General)

Controlling the N - and S -representability of the second-order reduced density matrix: The doublet-state case

REA Auditado

A purification procedure that simultaneously corrects the N- and S-representability main defects of a second-order reduced density matrix (2RDM), second-order hole reduced density matrix (2HRDM), and second-order G matrix is presented here. In this purifying procedure, the generalized unitarily invariant second-order matrix decomposition [D. R. Alcoba, Int. J. Quantum Chem. 97, 776 (2004)] for the 2RDM and the 2HRDM as well as for the G matrix is combined with the S-representability conditions. In particular, here we will focus our attention on the RDMs corresponding to doublet states.

Tema: general: 

• Ciencias

Accurate ab initio intermolecular potential energy surface for the quintet state of the O2(3Σ(-)(g))-O2((3)Σ(-)(g)) dimer

REA Auditado

A new potential energy surface (PES) for the quintet state of rigid O2(3Σ(-)(g))+O2((3)Σ(-)(g)) has been obtained using restricted coupled-cluster theory with singles, doubles, and perturbative triple excitations [RCCSD(T)]. A large number of relative orientations of the monomers (65) and intermolecular distances (17) have been considered. A spherical harmonic expansion of the interaction potential has been built from the ab initio data. It involves 29 terms, as a consequence of the large anisotropy of the interaction.

Tema: general: 

• Ciencias

Possible ω bound states in nuclei produced with the (γ,p) reaction

REA Auditado

We perform calculations for ω production in nuclei by means of the (γ,p) reaction for photon energies and proton angles suited to currently running and future experiments in present laboratories. For some cases of possible ω optical potentials, we find that clear peaks are observable when a good resolution in the ω energy is available.

Tema: general: 

• Ciencias

STS.436 Cold War Science, Spring 2004

REA Auditado

This course examines the history and legacy of the Cold War on science, looking predominantly at examples in the United States. It begins by exploring scientists’ new political roles after World War II, ranging from elite policy-makers in the nuclear age to victims of domestic anti-Communism. The course next examines the changing institutions in which the physical, biological, and social sciences were conducted during the postwar decades, investigating the links between institutions and epistemology. The course closes by considering the place of science in the post-Cold-War era.

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ciencias Computacionales

Isotopes and Atomic Mass - Isotopes, Isotope, Atomic Mass - PhET

RE Sugerido

Informacion sobre los isotopos y la masa atomica

Tema: general: 

• Ciencias›Ciencias (General)

The Brazilian time and frequency atomic standards program

REA Auditado

Cesium atomic beam clocks have been the workhorse for many demanding applications in science and technology for the past four decades. Tests of the fundamental laws of physics and the search for minute changes in fundamental constants, the synchronization of telecommunication networks, and realization of the satellite-based global positioning system would not be possible without atomic clocks. The adoption of optical cooling and trapping techniques, has produced a major advance in atomic clock precision. Cold-atom fountain and compact cold-atom clocks have also been developed.

Tema: general: 

• Ciencias›Ciencias (General)

Atomic short-range order determination in gold-25 atomic percent iron and nickel-12.5 atomic percent silicon: A synchrotron x-ray diffuse scattering study

REA Auditado

The short-range order (SRO) structure of a Gold-25 atomic percent Iron single crystal was studied using wide-angle diffuse synchrotron x-radiation scattering at room temperature. Two heat-treatments were investigated; a 400$\sp\circ$C aging treatment for two days and a second at 440$\sp\circ$C for five days, both preceded by solution treatment in the single-phase field and water-quenched to room temperature. Evolution of the SRO structure with aging was determined by fitting the two sets of Cowley-Warren SRO parameters to a pair of 140,608-atom models.

Tema: general: 

• Ingeniería y Ciencias Aplicadas›Ingeniería›Ingeniería Civil y Ciencia de los Materiales