The 4d95p transitions in the tenth spectrum of cesium, Cs X

1991 ◽  
Vol 69 (1) ◽  
pp. 24-25 ◽  
Author(s):  
Y. N. Joshi ◽  
B. Arcimowicz
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Least Squares ◽  
Wavelength Region ◽  
Hartree Fock

The spectrum of cesium was photographed in the 850–400 Å (1 Å = 10−10 m) wavelength region. Nineteen lines were interpreted as transitions between the 4d95s and 4d95p configurations. All levels of the 4d10, 4d95s, and 4d95p configurations were established. Least-squares-fitted parametric calculations and Hartree–Fock ab initio calculations support the analyses.

3d-Shell excitation in photoabsorption of atomic selenium

1988 ◽  
Vol 66 (4) ◽  
pp. 326-329 ◽  
Author(s):  
Y. N. Joshi ◽  
M. Mazzoni
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Least Squares ◽  
Flash Pyrolysis ◽  
Hartree Fock ◽  
Photoabsorption Spectrum ◽  
Transition Array

The photoabsorption spectrum of the inner 3d-shell excitation of atomic selenium was observed in the 500–170 Å region using the flash-pyrolysis technique. The observations, aided by the Hartree–Fock ab initio calculations and least squares fitted parametric calculations, have lead to the classification of 15 lines in the 4p4–3d94s24p5 transition array and 26 lines in the 4p4–3d94s24p4np transitions. Two series ionization limits have been calculated as 517 500 cm−1 (64.15 eV) and 530 000 cm−1 (67.70 eV).

The vibrational spectrum, barrier to internal rotation, and ab initio calculations of 2-chloropropane

1991 ◽  
Vol 69 (11) ◽  
pp. 1845-1856 ◽  
Author(s):  
J. F. Sullivan ◽  
Aiying Wang ◽  
Mei-Shiow Cheng ◽  
J. R. Durig
Keyword(s):  
Vibrational Spectrum ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Internal Rotation ◽  
Far Infrared ◽  
Basis Sets ◽  
Equilibrium Geometry ◽  
Coupling Term ◽  
Hartree Fock ◽  
Experimental Values

The Raman spectra (3200–50 cm−1) of gaseous, liquid, and solid 2-chloropropane-d3 (isopropyl-d3 chloride), CH3(CD3)CHCl, and the infrared spectra (3200–50 cm−1) of the gas and solid have been recorded. The torsional transitions observed in the far infrared spectrum of the gaseous sample recorded at a resolution of 0.10 cm−1 between 265 and 135 cm−1 were analyzed in terms of the semirigid rotor model. An effective barrier of 1378 ± 4 cm−1 (3.94 ± 0.01 kcal/mol), cosine–cosine coupling term of 166 ± 10 cm−1 (0.47 ± 0.03 kcal/mol), and sine–sine coupling term of −173 ± 1 cm−1 (−0.49 ± 0.01 kcal/mol) were determined by fitting ten observed frequencies arising from the CH3 and CD3 torsions. The assignment of the 27 fundamentals is given and discussed. A complete equilibrium geometry, barrier to internal rotation, and vibrational frequencies have been determined by ab initio Hartree–Fock gradient calculations employing either 3-21G* or 6-31G* basis sets for both the d0 and d3 species. These calculated results are compared to the experimental values as well as to the corresponding quantities for some similar molecules. Key words: 2-chloropropane, vibrational spectrum; ab initio calculations; barrier to internal rotation.

Ab initio studies on 1,2-oxathietane, Z and E 3,4-dimethyl-1,2-oxathietane, and their products of formal [σ2s + σ2a] cycloreversion

1988 ◽  
Vol 66 (8) ◽  
pp. 1890-1894 ◽  
Author(s):  
Ali Naghipur ◽  
J. William Lown ◽  
Duli C. Jain ◽  
Anne-Marie Sapse
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Ground State ◽  
Atomic Charges ◽  
The Novel ◽  
Hartree Fock ◽  
Plausible Mechanism

Ab initio calculations at the level of 3-21G* SCF and MP3/3-21G* have been performed on the novel heterocycle 1,2-oxathietane and the formal [σ2s + σ2a] cycloreversion products. Hartree–Fock calculations have been performed for the E and Z 3,4-dimethyl-1,2-oxathietanes and their corresponding cycloreversion products. The calculations afford fully geometry optimized conformations, energies, net atomic charges, and HOMO values for the heterocycles. 1,2-Oxathietane is found to be close in energy to the sum of energies of either pair of its cycloreversion products. The most plausible mechanism of cycloreversion features the formation of ground state formaldehyde and thioformaldehyde via a biradical intermediate. This result is in accord with the lack of detection of chemiluminescence with the 1,2-oxathietanes, in contrast to the 1,2-dioxetanes.

Ab initio studies of isocyanatoborane and difluoroisocyanatoborane; bent or linear BNCO chains?

1991 ◽  
Vol 69 (6) ◽  
pp. 1000-1005 ◽  
Author(s):  
Susan Ellis ◽  
Edward G. Livingstone ◽  
Nicholas P. C. Westwood
Keyword(s):  
Carbon Atom ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Potential Surface ◽  
Energy Difference ◽  
Basis Set ◽  
Basis Sets ◽  
Hartree Fock ◽  
Split Valence ◽  
Valence Basis Set

Ab initio calculating at the 3-21G, 6-31G*, 6-31G**, 6-311G*, and 6-311G** Hartree–Fock levels, have been performed on the unknown H2BNCO and F2BNCO molecules in order to establish the geometries of these isoelectronic propadienone analogues. For H2BNCO the double split valence basis sets lead to linear BNCO chains, whereas either a triple split valence basis set, or the inclusion of correlation to second order (MP2/6-31G*) gives trans-bent structures. These have angles at nitrogen of 153.6° (6-311G*) or 149.9° (MP2/6-31G*), with the potential surface for angle bending extremely flat, and 0.5 kJ mol−1 (6-311 G*) or 1.12 kJ mol−1 (MP2/6-31 G*) separating the C2v and Cs structures. For the bent structures there is a small trans-bend (4–6°) at the carbon atom. The F2BNCO molecule is also linear at the 3-21G level, but is, however, already trans-bent (145.6° at nitrogen, 175.9° at carbon) at the 6-31G* Hartree–Fock level; 1.47 kJ mol−1 separates the bent and linear structures. The triple split valence basis set 6-311G* leads to a further decrease in the angle at nitrogen (141.0°), and a similar NCO angle (175.9°), with the bent structure favoured by 3.85 kJ mol−1. MP2/6-31G* calculations give a minimum with an angle at nitrogen of 140.2°, and a bent-linear energy difference of 3.58 kJ mol−1. Key words: ab initio calculations, isocyanatoboranes, structures, quasilinearity, propadienone analogues.

Atomic Orbitals from Compton Profiles

1993 ◽  
Vol 48 (1-2) ◽  
pp. 221-226 ◽  
Author(s):  
Hartmut Schmider ◽  
Vedene H. Smith, Jr.
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Least Squares ◽  
Density Matrices ◽  
Expectation Values ◽  
Position Space ◽  
Reduced Density Matrices ◽  
Atomic Orbitals ◽  
Reduced Density

Abstract A recently developed method for the least-squares reconstruction of one-particle reduced density matrices from one-particle expectation values has been applied to isotropic Compton profiles of neon from the literature. The resulting densities in momentum and position space are compared with the ones obtained from ab-initio calculations.

4d75s–4d75p Transitions in Ag IV

1983 ◽  
Vol 61 (1) ◽  
pp. 36-39 ◽  
Author(s):  
Th. A. M. vanKleef ◽  
Y. N. Joshi
Keyword(s):  
Least Squares ◽  
Wavelength Region ◽  
Normal Incidence ◽  
Hartree Fock ◽  
Least Squares Fit

The spectrum of silver was photographed in the wavelength region 400–2300 Å on a variety of spectrographs including a 10.7 m normal incidence vacuum spectrograph. The sources used were a sliding spark and a triggered spark. On the basis of these observations, 12 missing levels of the 4d75p configuration and all levels of the 4d75s configuration have been established. The least squares fit and Hartree–Fock calculations support the analysis. Seven hundred and twelve additional lines have been classified in this spectrum, 40 of which are doubly classified and four are trebly classified.

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