Floating spherical gaussian orbital (FSGO) studies with a model potential: some open-shell systems

A gaussian based model potential is used within the FSGO formalism to study a series of open-shell systems (e.g. LiH⁺, NaH⁺, Li⁺₂ and LiNa⁺). Results for calculated equilibrium geometries and dissociation energies are compared to the corresponding quantities from available all-electron ab initio studies and other more elaborate theoretical estimates. The overall agreement is quite satisfactory.     

Floating spherical Gaussian orbital (FSGO) studies with a model potential: Application to two-valence-electron systems

A Gaussian based model potential is used within FSGO formalism to study a series of two-valence-electron diatomics (Li₂, Na₂, K₂, LiH, NaH, KH, MgH⁺, CaH⁺, LiNa, LiK and NaK) and triatomic ions (H₂Li⁺, H₂Na⁺, Li₂Na⁺, Na₂Li⁺, Li ₃ ⁺ , Na ₃ ⁺ , Li₂H⁺ and Na₂H⁺). Results for calculated equilibrium geometries, force constants, and energy changes for certain chemical reactions are compared to the corresponding quantities from available all-electronab initio studies and experimental results. The predicted results are generally satisfactory.Aided by grants to the University of North Carolina from the National Institute of Health and the National Science Foundation.     

Electron momentum distributions and compton profiles of some alkali halides with FSGO model

The electron momentum distributions (EMD's) and Compton profiles (CP's) of LiF, LiCl, NaF and NaCI have been calculated using the floating spherical gaussian orbital (FSGO) model wavefunctions. The calculated FSGO Compton profiles are in good agreement with the available experimental data considering the simplicity of the model used. The calculated EMD and CP values in these systems are nearly equal to the sum of the contributions of respective cations and anions.     

The floating spherical gaussian orbital model and shape of B2H5 ion

The FSGO model has been used to make ab initio calculations of the geometry of B₂H ion. The results indicate that the acetylenic structure has the lowest energy (?43.881 a.u.) and the planar structure has the highest energy (?43.838 a.u.). The energy of the non-symmetric structure is only slightly higher (?43.879 a.u.) than that of the acetylenic one. Results of CNDO /2 calculations reported here also predict the acetylenic structure to be the most stable one.     

Floating spherical Gaussian orbital model study of average electric polarisabilities and magnetic susceptibilities: Some aliphatic hydrocarbons

Floating spherical Gaussian orbital model is used to discuss the average electric polarisabilities and magnetic susceptibilities of a series of hydrocarbons. It has been noticed that the core contributions are negligibly small and these quantities (average electric polarisabilities and magnetic susceptibilities) can be well estimated from contributions localised on bond Gaussians.     

Conductance studies on the interaction of D-glucose with alkali halides in water and formamide

The interaction of D-glucose with alkali halide in aqueous and formmide solutions has been studied by employing conductance measurements. Our results showed a break at the saturation temperature indicating a transition in the conductance values. This behaviour is explained in terms of solute-solvent interactions involved in the electrolyte-solvent-nonelectrolyte systems.     

A floating spherical gaussian orbital model of molecular structure. XII. Analysis of energy terms affecting the geometry of the water molecule

The energy terms arising in the water calculation by the FSGO method are analyzed as a function of the bond angle in order to gain insight into the reasons for the particular equilibrium configuration. The analysis is made in terms of symmetrically orthogonalized orbitals so as to exclude three- and four-orbital electron repulsion terms.     

Exact solution of an electron trapped in a spherical cavity and applications to the F center in alkali halides

An exact solution of the Schrödinger equation for an electron trapped in a spherical cavity of the Krumhansl and Schwartz potential is given. Transition energies (1S 2P) of the F electron are reported for 16 MX systems and the normalization constants of the wave functions are given for the 1S and 2P states. The shape of absorption bands of F-centers is also discussed and the calculated oscillator strengths for the transition 1S 2P of various crystals are given.Work supported in part by the National Science Foundation.Alfred P. Sloan Fellow.     

Adsorption calorimetric studies of copper(I) halides

Adsorption properties of CuBr and CuI with respect to O₂ and CO₂ at 298 K have been examined. Two forms of CO₂ adsorption with adsorption heats of q=28 and 10 kJ/mol for CuBr and q=14 and 9 kJ/mol for CuI have been found. Low values of the adsorption entropy indicate the high mobility of CO₂ molecules in the adsorption layer.

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CuBr CuI CO₂ 298 . CO₂ 28 10 / CuBr 14 9 / CuI. CO₂ .

     

Floating spherical gaussian orbital model study of some organometallic systems. I. LiCH3, HBeCH3, and CH3BeCH3

The floating spherical Gaussian orbital method has been used to study the equilibrium geometries and electronic structures of some organometallic systems like LiCH₃, HBeCH₃, and CH₃BeCH₃. The predicted geometries are in good agreement with other theoretical estimates and available experimental results. Electron transfer values from carbon to metal atom and bond energies of Li? C and Be? C bonds are estimated and discussed. The wave functions obtained here have also been used to predict the electron momentum distributions and Compton profiles for LiCH₃, HBeCH₃, and CH₃BeCH₃.     

Some neutral three-coordinate complexes of mercury(II) halides and pseudohalides with N-methylnicotinamide

Coordination compounds of mercury(II) chloride, bromide, cyanide and thiocyanate with N-methylnicotinamide, a potentially bidentate ligand, have been prepared. The complexesisolated have 1∶1 (metal:ligand)stoichiometry. Molecular weight measurements in molten camphor indicate that the mercury (II) chloride and bromide complexes are monomeric. Based on conductance values, molecular weight determinations and infrared spectral data, it is inferred that in the solid state in all these complexes the metal ion has a coordination number three and is bonded to the N-methylnicotinamide via its pyridine ring nitrogen, and is terminally bonded to the halogen/pseudohalogens.     

Review article: ion pair potentials for alkali halides and some applications to liquids and defect studies

Abstract

We review the basis on which interionic potentials for alkali halides are obtained. We find that the sizes of the van der Waals terms are known poorly and that the polarizable ion models lack the necessary thermodynamic corrections, however small they may be, to fit low temperature properties of the solid. Although the quantum statistical calculations indicated some damping of van der Waals interactions due to ionic overlap, a systematic study of the basic and modified approaches shows them to be unsatisfactory.     

Effect of halides and alkali cations on the Zn(Hg)/Zn(II) electrode reactions

The title subject has been studied by galvanostatic single-pulse, chronopotentiometric and equilibrium measurements on the Zn(Hg)/Zn(II) electrode in x M KI+(1?x) M KCl (x from 0 to 1), 1 M KBr and 1 M MeCl (Me=Li, Na, K and Cs) solutions of pH 3 at 25°C. Quantitative information about the effect of specifically adsorbed halides on the rates of the Zn(II)/Zn(I) and the Zn(I)/Zn(Hg) steps is obtained separately (for the latter step mainly at potentials near ?1.0 V(SCE)), and the latter step seems to be more influenced than the former by the adsorption. An attempt is made to correlate the adsorption effect on the rate of the Zn(II)/Zn(I) step to double-layer parameters according to recent models for such effects. The extra current observed at potentials where the halides are adsorbed, seems to vary with the surface activity of the specifically adsorbed ion. The lack of any observed kinetic effect of Cs⁺, which is specifically adsorbed at these potentials, is possibly due to the Cs⁺ specific adsorption enhancing the Cl^? specific adsorption and vice versa, so that the decelerating and accelerating effects by these ions may cancel each other.     

Assembly of 2D ionic layers by reaction of alkali halides with the organic electrophile 7,7,8,8-tetracyano-p-quinodimethane (TCNQ)

Sublimation of alkali halides (NaCl and LiCl) onto a pre-assembled hydrogen-bonded layer of TCNQ on Au(111) resulted in the formation of 2D ionic layers via a direct charge-transfer reaction without involvement of the substrate. The presented approach allows for the fabrication of different ionic layers, decoupled from the substrate and offering new, potentially interesting properties.     

Morphological study on diffusion‐limited aggregates of poly(ethylene oxide) on alkali halides

When poly(ethylene oxide) was crystallized on a fresh cleavage surface of alkali halides from solution in isoamyl acetate, diffusion‐limited‐aggregate dendrites were formed. Their patterns varied, depending on the kind of substrate on which the poly(ethylene oxide) crystallized: On a KCl substrate, rather ordered dendrites grew with fibrillar crystallites aligning roughly in the 〈110〉_KCl direction, and coarse dendritic clusters formed on NaCl and KBr during the initial stage of their growth. The dendrites grew and matured to sheet the whole surface of alkali halides with a uniform thickness, and subsequently, tetragonal lamellae formed on it through the spiral growth mechanism or the primary nucleation process. Tetragonal lamellar crystals grew with their diagonals parallel to fibrillar crystallites of dendrites. Their orientation did not result from direct, epitaxial contact with the alkali halide substrate but depended on the fibrillar orientation of the underlying sheeted layer. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2421–2430, 2002     

Some solutions of a cell model for a suspension of spherical vesicles in osmophoresis

The problem of the osmophoretic motion of a homogeneous suspension of identical spherical vesicles is analyzed in the limit of negligible Reynolds and Peclet numbers. The effects of interaction among individual vesicles are taken into explicit account by employing a unit cell model which is known to provide good predictions for the sedimentation of monodisperse suspensions of spherical particles. The appropriate equations of conservation of mass and momentum are solved for each cell, in which a spherical vesicle is envisaged to be surrounded by a concentric shell of suspending fluid, and the osmophoretic velocity of the vesicle is calculated for various cases. Analytical expressions of this mean vesicle velocity are obtained in closed form as functions of the volume fraction of the vesicles. Comparisons between the approximate ensemble-averaged osmophoretic velocity of a test vesicle in a dilute suspension and our cell-model results are made.