Ab initio study of valence-state potential energy curves of nitrogen

1982 ◽  
Vol 86 (8) ◽  
pp. 1305-1314 ◽  
Author(s):  
W. C. Ermler ◽  
A. D. McLean ◽  
R. S. Mulliken
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Valence State ◽  
Potential Energy Curves ◽  
Ab Initio Study ◽  
State Potential

Ab initio molecular orbital studies of the potential energy curves for the low lying triplet states of Be2 and Be3

1988 ◽  
Vol 66 (8) ◽  
pp. 2034-2040 ◽  
Author(s):  
Ratnakar K. Gosavi ◽  
Otto P. Strausz
Keyword(s):  
Potential Energy ◽  
Triplet State ◽  
Ab Initio ◽  
Potential Energy Curves ◽  
Basis Set ◽  
Triplet States ◽  
Diradical Character ◽  
State Formula ◽  
State Potential ◽  
Gaussian Basis Set

Ab initio calculations with uniform quality gaussian basis set were carried out at the RHF-SCF and CI level on the potential energy curves of the low lying triplet states of Be2 and Be3. The lowest excited state, the [Formula: see text] state of Be2 is 26.0 kcal/mol higher in energy than the ground [Formula: see text] state, and 39.4 kcal/mol lower than the separated Be(1S0) + Be(3P) atoms, with the s, p, d basis set. The next higher triplet state, the 3Πg, is only 8.7 kcal/mol above the lowest [Formula: see text] state. The [Formula: see text] and 3Πu states lie comparatively much higher than the [Formula: see text] state. All the triplet state potential curves have a bonding nature. The lowest triplet state [Formula: see text] in Be3 with D∞h symmetry lies ~15 kcal/mol above the ground [Formula: see text] state, and 48.2 kcal/mol lower than the separated atoms, 2Be(1S0) + Be(3P). The [Formula: see text] state has 1,3-diradical character and in all the higher triplet states α spin electrons are delocalized among the three Be atoms. The next higher triplet state 3Πu is 7.7 kcal/mol above the lowest [Formula: see text] state. The [Formula: see text] and 3Πg states lie much higher than the [Formula: see text] and 3Πu states. Like the triplet states of Be2, all Be3 triplet states have a bonding nature. Reaction path studies on the Be(3P) energy transfer reactions, [Formula: see text] and [Formula: see text] show that these reactions do not feature any activation energy barrier.

Bound–free B2Σ+ –X2Π, A2Σ+ emission in the BAr van der Waals complex

1994 ◽  
Vol 72 (3) ◽  
pp. 821-827 ◽  
Author(s):  
Eunsook Hwang ◽  
Paul J. Dagdigian ◽  
Millard H. Alexander
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Van Der Waals ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Potential Energy Curves ◽  
Lower State ◽  
Fluorescence Emission Spectra ◽  
State Potential ◽  
Spectrally Resolved

Spectrally resolved bound–free fluorescence emission spectra for the excitation of several vibrational levels in the excited B2Σ+ electronic state of the van der Waals molecule 11BAr are presented. This excited state emits to the ground X2Π and low-lying A2Σ+ states, both of which correlate with the ground state atomic asymptote B(2p2P) + Ar. Because of the large differences in equilibrium internuclear separations, the emission occurs mainly to the repulsive walls. In order to gain more information on this portion of the potential energy curves, the experimental emission spectra were compared with simulated spectra derived from ab initio calculated B–Ar interaction potentials. The simulated spectra reproduce the experimental spectra well if the lower-state potential energy curves are shifted slightly inward. This discrepancy is consistent with our previous observation that the ab initio calculations slightly overestimate the vibrationally averaged internuclear separation, which we determined experimentally. This reflects the difficulty of accurately calculating weak van der Waals interaction energies.

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