33 research outputs found
All-Electron First Principles Calculations of the Ground and Some Low-Lying Excited States of BaI
Electronic structure and bonding of ozone
The ground and low-lying states of ozone (O(3)) have been studied by
multireference variational methods and large basis sets. We have
constructed potential energy curves along the bending coordinate for
(1,2) (1)A’, (1,2) (1)A ‘’, (1,2) (3)A’, and (1,2) (3)A ‘’ symmetries,
optimizing at the same time the symmetric stretching coordinate.
Thirteen minima have been located whose geometrical and energetic
characteristics are in very good agreement with existing experimental
data. Special emphasis has been given to the interpretation of the
chemical bond through valence-bond-Lewis diagrams; their appropriate use
captures admirably the bonding nature of the O(3) molecule. The
biradical character of its ground state, adopted long ago by the
scientific community, does not follow from a careful analysis of its
wave function. (C) 2008 American Institute of Physics
Electronic structure and bonding of the 3d transition metal borides, MB, M=Sc, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu through all electron ab initio calculations
The electronic structure and bonding of the ground and some low-lying
states of all first row transition metal borides (MB), ScB, TiB, VB,
CrB, MnB, FeB, CoB, NiB, and CuB have been studied by multireference
configuration interaction (MRCI) methods employing a correlation
consistent basis set of quintuple cardinality (5Z). It should be
stressed that for all the above nine molecules, experimental results are
essentially absent, whereas with the exception of ScB and CuB the
remaining seven species are studied theoretically for the first time. We
have constructed full potential energy curves at the MRCI/5Z level for a
total of 27 low-lying states, subsequently used to extract binding
energies, spectroscopic parameters, and bonding schemes. In addition,
some 20 or more states for every MB species have been examined at the
MRCI/4Z level of theory. The ground state symmetries and corresponding
binding energies (in kcal/mol) are (5)Sigma(-)(ScB), 76; (6)Delta(TiB),
65; (7)Sigma(+)(VB), 55; (6)Sigma(+)(CrB), 31; (5)Pi(MnB), 20;
(4)Sigma(-)(FeB), 54; (3)Delta(CoB), 66; (2)Sigma(+)(NiB), 79; and
(1)Sigma(+)(CuB), 49. (c) 2008 American Institute of Physics