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.

Ab initio MC–SCF ground‐state potential energy curves for LiH−, NaH−, and CsH−

1978 ◽  
Vol 68 (4) ◽  
pp. 1942-1950 ◽  
Author(s):  
Arnold M. Karo ◽  
Maureen A. Gardner ◽  
John R. Hiskes
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Ground State ◽  
Potential Energy Curves ◽  
State Potential

Potential energy curves and dipole moment of NF molecule with inner electron correlation

2015 ◽  
Vol 93 (12) ◽  
pp. 1544-1550 ◽  
Author(s):  
Mingjie Wan ◽  
Huafeng Luo ◽  
Chengguo Jin ◽  
Duohui Huang ◽  
Fanhou Wang
Keyword(s):  
Potential Energy ◽  
Excited States ◽  
Correlation Energy ◽  
Dipole Moments ◽  
Electronic States ◽  
Spectroscopic Properties ◽  
Potential Energy Curves ◽  
Basis Set ◽  
Triplet States ◽  
Singlet And Triplet States

The potential energy curves and dipole moments for the low-lying electronic states of the NF molecule are found by using highly accurate multireference configuration interaction plus the Davidson correction with the AV5Z basis set. All 16 electrons are used in the correlation energy calculations, which are used to characterize the spectroscopic properties of a manifold for singlet and triplet states. X3Σ–, a1Δ, b1Σ+, A3Π, 23Σ–, 23Π, 21Δ, 33Σ–, 13Σ+, and 13Δ electronic states correlate with the two lowest dissociation channels N(4Su) + F(2Pu) and N(2Du) + F(2Pu) are investigated. Note that the b1Σ+ state has two depth wells, but only one depth well was observed in the experiment. The spectroscopic parameters (Re, ωe, ωeχe, De, Be, and Te) are derived, which are in excellent agreement with the available experimental data and the other theoretical values. The molecular parameters and dipole moments for the ground and excited states are also obtained.

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

Rotational de-excitations of C3H+ (1Σ+) by collision with He: new ab initio potential energy surface and scattering calculations

2020 ◽  
Vol 494 (4) ◽  
pp. 5675-5681 ◽  
Author(s):  
Sanchit Chhabra ◽  
T J Dhilip Kumar
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Cross Sections ◽  
Energy Surface ◽  
Molecular Ions ◽  
Basis Set ◽  
Rate Coefficients ◽  
Close Coupling ◽  
Collisional Rate Coefficients

ABSTRACT Molecular ions play an important role in the astrochemistry of interstellar and circumstellar media. C3H+ has been identified in the interstellar medium recently. A new potential energy surface of the C3H+–He van der Waals complex is computed using the ab initio explicitly correlated coupled cluster with the single, double and perturbative triple excitation [CCSD(T)-F12] method and the augmented correlation consistent polarized valence triple zeta (aug-cc-pVTZ) basis set. The potential presents a well of 174.6 cm−1 in linear geometry towards the H end. Calculations of pure rotational excitation cross-sections of C3H+ by He are carried out using the exact quantum mechanical close-coupling approach. Cross-sections for transitions among the rotational levels of C3H+ are computed for energies up to 600 cm−1. The cross-sections are used to obtain the collisional rate coefficients for temperatures T ≤ 100 K. Along with laboratory experiments, the results obtained in this work may be very useful for astrophysical applications to understand hydrocarbon chemistry.

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