Efficient diffuse function-augmented basis sets for anion calculations. III. The 3-21+G basis set for first-row elements,Li–F

The relatively small diffuse function-augmented basis set, 3-21+G, is shown to describe anion geometries and proton affinities adequately. The diffuse sp orbital exponents are recommended for general use to augment larger basis sets.     

Vibrational spectra,force constants and mean amplitudes of vibrations of urea and deuterated urea

The vibrational spectra of urea and deuterated urea have been recorded. Using a most general potential function, the force constants and the mean amplitudes of vibration have been calculated.     

Temperature dependence of dielectric constant of crystals with fluorite structure

The experimental data on the temperature variation of dielectric constant of six crystals with fluorite structure are analysed using an approach proposed by Havinga and Bosman for ionic crystals. The temperature variation of dielectric constant is resolved in three components related to the thermal expansion, the pressure dependence of dielectric constant and the temperature variation of polarizability (theA, B, C terms). In the present work, theB term is calculated semiempirically, such that the analysis can be extended to crystals like EuF₂ for which high pressure dielectric constant data are not available. For the first time, such calculations have been made for EuF₂ and PbF₂ at elevated temperatures. TheC term, which is related to the temperature variation ofir polarizability is seen to play a dominant role in determining the temperature variation of dielectric constant.     

Measurement of ultrashort optical pulses by two-photon photoconductivity techniques

Two-photon conductivity in GaAs and CdS_0·5Se_0·5 were investigated with modelocked Nd:glass laser pulse excitation, with a view to determine their suitability for picosecond pulsewidth measurement. The contrast ratio using GaAs as twophoton conductor was 1.8 and it increased to 2.4 when CdS_0·5Se_0·5 was used. The improved contrast ratio in the case of CdS_0·5Se_0·5 was partly due to the improved resolution of the crystal (2 ps) and partly due to the extended square-law region.     

Conjugate Maps,Subgradients and Conjugate Duality in Set-Valued Optimization

Using the concept of supremum/infimum of a set, defined in terms of the closure of the set, we introduce the notions of conjugate and biconjugate maps as well as that of subgradients of a set-valued map. Conjugate duality results are also established for a set-valued optimization problem.     

Nonnegative Generalized Inverses and Interval Linear Programs

Connections between nonnegative generalized inverses and interval linear programs form the subject matter of this article. Characterizations of nonnegativity of the Moore–Penrose inverse and the group inverse are presented and their role in the study of a special class of optimization spaces, namely, Ben-Israel–Charnes spaces is brought out. The interplay between Ben-Israel–Charnes spaces and other notions of generalized inverse positivity are also studied.     

Brønsted acid assisted activation of imide carbonyl group: regioselective synthesis of isoindoloisoquinolinone alkaloid (±)-nuevamine

Activation of imide carbonyl group with trifluoromethanesulfonic acid facilitates the intramolecular cyclization of phenethylphthalimides to give a fused isoindoloisoquinolinone skeleton. The first one pot regioselective synthesis of isoindoloisoquinolinone alkaloid (±)-nuevamine has been successfully executed using this methodology.