Ab initio calculation for properties of hydrogen bonded complexes H3N⋯HCN,HCN⋯HCN,HCN⋯HF,H2O⋯HF

Self Consistent Field calculations, using TZ+2P basis sets, are reported on four hydrogen-bonded complexes. Vibrational frequencies, rotational constants, infrared and raman intensities are compared with available experimental data. The basis set superposition error is shown not to be important for the calculation of these properties with this basis set.     

A relationship between Gel'fand-Levitan and Marchenko kernels

A new integral equation which relates the output kernels of the Gel'fand-Levitan and Marchenko inverse scattering equations in a continuous range of their variables is specified. Structural details of this integral equation are studied when theS-matrix is a rational function, and the output kernels are separable in terms of Bessel, Hankel and Jost solutions.     

Trace preserving linear transformations on matrix algebras

A characterization is given for all linear transformations on a matrix algebra which preserve (1) the trace (2) the unit matrix (3) the trace and the second elementary symmetric function of the eigenvalues.     

Higher analytic derivatives. I. A new implementation for the third derivative of the SCF energy

This is the first of a series of papers on the ab initio calculation of the second, third, and fourth derivatives of the energy with respect to nuclear coordinates. The knowledge of these derivatives yields anharmonic spectroscopic constants. Here, we present efficient formulae for the analytic evaluation of these derivatives for closed-shell SCF wave functions. We discuss our implementation of the third derivative formula, in particular the integral and vectorization procedures. Applications are reported for H₂S, CHOF, and HCCF.     

Reentrant isotropic phase in a discotic liquid crystal mixture

We have used X-ray diffraction and optical microscopy to study binary mixtures of 2,3,7,8,12,13-hexa-n-tetradecanoyloxy- and 2,3,7,8,12,13-hexa(4-n-undecyloxybenzoyloxy) truxenes. Our measurements confirm the existence of a reentrant isotropic phase, which is however always preceded by a mixed phase region rather than by a pure columnar phase. The nematic N_D phase displays an anomalously negative thermal expansion coefficient. We speculate on mechanisms for reentrancy in discotic mesogens.     

Predictions of a microscopic model of p-A scattering

Proton scattering from nuclei can be predicted using optical Poten tials formed by full folding an effective two-nucleon interaction with detailed nuclear structure. Excellent results are found in comparison with measured total reaction as well as with measured differential cross sections.     

Adsorption effects on resonant charge transfer in atom-surface scattering

The probability of positive ionization of an atom impinging on a solid surface is calculated by numerical solution of the equations of motion of the time-dependent molecular orbitals of the system. The model is applied to the scattering of Na atoms, in the energy range 50–1000 eV, from a W(110) surface. The presence of Na adatoms is considered and found to hinder the ionization process. This reduction in the charge-transfer probability arises because of the lowering of the surface work function brought about by increasing adatom concentration.     

Algebraic hulls and the følner property

A. I. was partially supported by NSF grants DMS 9001959, DMS 9100383 and DMS 8505550. A. N. was partially supported by the Israel National Academy of Science and Humanities — Wolfson grant.