Structure and Phase Composition of a W-Ta-Mo-Nb-V-Cr-Zr-Ti Alloy Obtained by Ball Milling and Spark Plasma Sintering.

In this paper, the structural characteristics of a W-Ta-Mo-Nb-V-Cr-Zr-Ti non-equiatomic refractory metal alloy obtained by spark plasma sintering (SPS) of a high-energy ball-milled powder mixture are reported. High-energy ball milling resulted in the formation of particle agglomerates ranging from several tens to several hundreds of micrometers. These agglomerates were composed of micrometer and submicrometer particles.

Radiative cooling of HO and its deuterated isotopologues.

In conjunction with ab initio potential energy and dipole moment surfaces for the electronic ground state, we have made a theoretical study of the radiative lifetimes for the hydronium ion HO and its deuterated isotopologues. We compute the ro-vibrational energy levels and their associated wavefunctions together with Einstein coefficients for electric dipole transitions. A detailed analysis of the stability of the ro-vibrational states has been carried out and the longest-living states of the hydronium ions have been identified.

Roto-translational states of the interstitial molecular hydrogen in silicon: A theoretical study.

A theoretical study of the interstitial molecular hydrogen in the silicon single-crystal is reported. H2 and Si have been approximated as a rigid object and a static matrix, respectively. A five-dimensional numerical-analytical representation of an ab initio potential energy surface of the system has been constructed.

Calculation of rovibronic intensities for triatomic molecules in double-Renner-degenerate electronic states: Application to the X (2)A(") and A (2)A(') electronic states of HO(2).

An algorithm and a computer program implementing it are presented for calculation of the rovibronic intensities for a triatomic molecule in a "double-Renner-degenerate" electronic state. The program has been applied to investigate, by theoretical simulation, the absorption spectrum of HO(2) in the X (2)A(") and A (2)A(') electronic states. The spectrum simulations are based on potential energy functions, electric dipole moment functions, and electric dipole transition moment functions constructed from ab initio values calculated at the core-valence MR-SDCI+Q/[cc-pVQZ (H), aug-cc-pCVQZ (O)] level of theory.

Theoretical rotation-torsion energies of HSOH.

The rotation-torsion energies in the electronic ground state of HSOH are obtained in variational calculations based on a newly computed ab initio CCSD(T)/aug-cc-pV(Q+d)Z potential energy surface. Using the concept of the reaction path Hamiltonian, as implemented in the program TROVE (theoretical rovibrational energies), the rotation-vibration Hamiltonian is expanded around geometries on the torsional minimum energy path of HSOH. The calculated values of the torsional splittings are in excellent agreement with experiment; the root-mean-square (rms) deviation is 0.

The double Renner effect in the X(2)A" and A(2)A' electronic states of HO(2).

A theoretical investigation of the X(2)A" and A(2)A' electronic states of the HO(2) radical is reported. Both electronic states have nonlinear equilibrium geometries and they correlate with a (2)Pi state at linear geometries so that they exhibit the Renner effect. In highly excited bending states, there is tunneling between two equivalent minima (with geometries where the H nucleus is bound to one, or the other, of the two O nuclei), and the two linear geometries H-O-O and O-O-H become accessible to the molecule.

Theoretical study of the double Renner effect for A2Pi MgNC/MgCN: higher excited rovibrational states.

The authors report here the implementation of a newly developed, highly efficient matrix diagonalization routine in the DR program [T. E. Odaka et al.

Positron binding energies for alkali hydrides.

Ab initio multireference single- and double-excitation configuration interaction (MRD-CI) calculations are carried out to study the interactions of positrons with the members of the alkali hydride class of molecules. A new computer program has been constructed for this purpose that makes use of the Table-Direct-CI method for construction of the required Hamiltonian matrixes and electronic/positronic wave functions. The calculations indicate that the binding energy (positron affinity PA) of a single positron to these systems increases by an increment of 0.