Polarization functions for first and second row atoms in Gaussian type MO-SCF calculations

1970 ◽  
Vol 17 (3) ◽  
pp. 199-208 ◽  
Author(s):  
B. Roos ◽  
P. Siegbahn
Keyword(s):  
Gaussian Type ◽  
Polarization Functions ◽  
Scf Calculations

The effect of p, d, and f Gaussian polarization functions on the computed one-electron properties of AHn oxygen and sulfur hydrides

1978 ◽  
Vol 56 (4) ◽  
pp. 543-551 ◽  
Author(s):  
Raymond Poirier ◽  
Roy Kari
Keyword(s):  
Basis Sets ◽  
Gaussian Type ◽  
Field Gradients ◽  
Isoelectronic Series ◽  
Monotonic Convergence ◽  
Polarization Functions ◽  
Scf Calculations ◽  
Made In ◽  
Lcao Mo

A series of LCAO-MO-SCF calculations, using various basis sets of Gaussian-type functions, has been made in order to study the effects of p, d, and f polarization functions on calculated one-electron properties for a 10-electron isoelectronic series of oxygen hydrides and for an 18-electron series of sulfur hydrides. Conclusions from these results suggest that several one-electron properties have a predictable, although not monotonic convergence pattern. Except for calculated field gradients, f GPF's have only a small effect on the calculated values.

Bonding in the P(PH3)2 and N(PH3)2 Cations. An ab initio Study

1985 ◽  
Vol 40 (9) ◽  
pp. 1149-1151 ◽  
Author(s):  
Wolfgang W. Schoeller
Keyword(s):  
Ab Initio ◽  
Phosphorus Atom ◽  
Negative Charge ◽  
Ab Initio Study ◽  
Polarization Functions ◽  
D Orbitals ◽  
Dipolar Structure ◽  
Scf Calculations

Ab initio SCF calculations at a double-ζ level were perform ed on the cations N(PH3)2+ and P(PH3)2+. Although both structures are isoelectronic, their bonding situation is different. The latter corresponds to a dipolar structure (phosphide) with considerable negative charge at the central phosphorus atom. The d-orbitals contribute to bonding as polarization functions rather than participate in hybridization.

Geometries of the ground and first excited triplet states of thioformaldehyde

1981 ◽  
Vol 59 (22) ◽  
pp. 3200-3203 ◽  
Author(s):  
John D. Goddard
Keyword(s):  
Ground State ◽  
Reasonable Agreement ◽  
Basis Sets ◽  
Triplet States ◽  
Gaussian Basis Sets ◽  
Excited Triplet ◽  
Polarization Functions ◽  
Scf Calculations ◽  
Split Valence ◽  
Excited Triplet States

The geometries of the S0 and T1 states of thioformaldehyde are determined by ab initio SCF calculations with Gaussian basis sets ranging from minimal to double ζ plus both diffuse and polarization functions. The ground state geometries are all in reasonable agreement with experiment but for the n → π* triplet state split valence or double ζ basis sets yield unreasonably long CS bond distances.

Properties of atoms in molecules: structures and reactivities of boranes and carboranes

1992 ◽  
Vol 70 (2) ◽  
pp. 657-676 ◽  
Author(s):  
R. F. W. Bader ◽  
D. A. Legare
Keyword(s):  
Charge Density ◽  
Molecular Structures ◽  
Atoms In Molecules ◽  
Basis Set ◽  
Reduced Order ◽  
Atomic Interactions ◽  
Polarization Functions ◽  
Experimental Findings ◽  
Scf Calculations ◽  
Good Agreement

The energies, geometries, and charge distributions of the closo-, nido-, and arachno-boranes and closo-carboranes are determined in SCF calculations using a contracted (9s,5p) basis set of Huzinaga, supplemented with polarization functions. Good agreement is obtained between the experimental and calculated geometries. Molecular structures are assigned on the basis of the bond paths defined by the topology of the charge density using the theory of atoms in molecules. This theory is used to characterize the atomic interactions and to account for the stabilities of these electron-deficient systems. It is shown that their stability is a consequence of the delocalization of charge over the surfaces of the three- and four-membered rings of atoms that result from the formation of bonds of reduced order, a delocalization that is itself essential to the formation of the ring bonds. The Laplacian of the charge density is used to predict the sites of nucleophilic and electrophilic attack in these molecules, predictions that are in agreement with known experimental findings. Keywords: boranes, carboranes, charge density, Laplacian of ρ.

Theoretical predictions of the molecular structure of sulphur tetrafluoride

1975 ◽  
Vol 28 (9) ◽  
pp. 2069 ◽  
Author(s):  
L Radom ◽  
III HF Schaefer
Keyword(s):  
Basis Set ◽  
Basis Sets ◽  
Structure Theory ◽  
Equilibrium Geometry ◽  
Double Zeta ◽  
Theoretical Predictions ◽  
Self Consistent Field ◽  
Polarization Functions ◽  
Hypervalent Molecules ◽  
Scf Calculations

The equilibrium geometry of the SF4 molecule has been investigated by means of ab initio electronic structure theory. Self-consistent-field (SCF) calculations employing a minimum basis set (MBS) incorrectly predict SF4 to have a square- pyramidal (C4V) structure. The correct qualitative prediction of a C2V geometry is obtained with a basis of nearly double zeta quality. Comparable calculations on H2S and SF2 suggest that it may only be for hypervalent molecules containing sulphur that minimum basis sets are inappropriate. However, polarization functions seem to be necessary for an accurate prediction of S-F bond distances.

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