Abstract
Molecular dynamics studies of collisional relaxation of highly excited SO2 in an Ar bath are described. Most of the calculations use a newly developed global ab initio potential surface for SO2 that correctly describes the superoxide (SOO) and ring isomers of SO2 that occur as secondary minima on the ground-state potential surface at high energies (about 75% of the dissociation energy) above the C2v minimum. Rate constants for the S + O2 and O + SO reactions are calculated to test this surface, and to examine the importance of electronically excited states in the O + SO recombination. The Ar + SO2 collisions are described by summing the ab initio potential with empirical intermolecular potentials. The resulting average vibrational energy transfer, (ΔE), per collision is in good agreement with direct measurements (performed at energies where the secondary minima are not populated) at 1000 K, but the agreement is poorer at 300 K. The agreement is significantly better than was obtained in a previous theoretical study, and our results indicate that the use of improved intramolecular and intermolecular potentials is crucial to obtaining better results. The energy dependence of (ΔE) is found to be much stronger at energies where secondary minima on the potential surface are accessible; however, much of this effect is reproduced using a potential that has the same dissociation energy but not the secondary minima.
| Original language | English |
|---|---|
| Pages (from-to) | 389-403 |
| Number of pages | 15 |
| Journal | Faraday Discussions |
| Volume | 102 |
| DOIs | |
| Publication status | Published - 1995 |
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- Physical and Theoretical Chemistry
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Theoretical studies of collisional relaxation of highly excited SO2 in an Ar bath. / Lendvay, György; Schatz, George C; Harding, Lawrence B.
In: Faraday Discussions, Vol. 102, 1995, p. 389-403.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Theoretical studies of collisional relaxation of highly excited SO2 in an Ar bath
AU - Lendvay, György
AU - Schatz, George C
AU - Harding, Lawrence B.
PY - 1995
Y1 - 1995
N2 - Molecular dynamics studies of collisional relaxation of highly excited SO2 in an Ar bath are described. Most of the calculations use a newly developed global ab initio potential surface for SO2 that correctly describes the superoxide (SOO) and ring isomers of SO2 that occur as secondary minima on the ground-state potential surface at high energies (about 75% of the dissociation energy) above the C2v minimum. Rate constants for the S + O2 and O + SO reactions are calculated to test this surface, and to examine the importance of electronically excited states in the O + SO recombination. The Ar + SO2 collisions are described by summing the ab initio potential with empirical intermolecular potentials. The resulting average vibrational energy transfer, (ΔE), per collision is in good agreement with direct measurements (performed at energies where the secondary minima are not populated) at 1000 K, but the agreement is poorer at 300 K. The agreement is significantly better than was obtained in a previous theoretical study, and our results indicate that the use of improved intramolecular and intermolecular potentials is crucial to obtaining better results. The energy dependence of (ΔE) is found to be much stronger at energies where secondary minima on the potential surface are accessible; however, much of this effect is reproduced using a potential that has the same dissociation energy but not the secondary minima.
AB - Molecular dynamics studies of collisional relaxation of highly excited SO2 in an Ar bath are described. Most of the calculations use a newly developed global ab initio potential surface for SO2 that correctly describes the superoxide (SOO) and ring isomers of SO2 that occur as secondary minima on the ground-state potential surface at high energies (about 75% of the dissociation energy) above the C2v minimum. Rate constants for the S + O2 and O + SO reactions are calculated to test this surface, and to examine the importance of electronically excited states in the O + SO recombination. The Ar + SO2 collisions are described by summing the ab initio potential with empirical intermolecular potentials. The resulting average vibrational energy transfer, (ΔE), per collision is in good agreement with direct measurements (performed at energies where the secondary minima are not populated) at 1000 K, but the agreement is poorer at 300 K. The agreement is significantly better than was obtained in a previous theoretical study, and our results indicate that the use of improved intramolecular and intermolecular potentials is crucial to obtaining better results. The energy dependence of (ΔE) is found to be much stronger at energies where secondary minima on the potential surface are accessible; however, much of this effect is reproduced using a potential that has the same dissociation energy but not the secondary minima.
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U2 - 10.1039/FD9950200389
DO - 10.1039/FD9950200389
M3 - Article
VL - 102
SP - 389
EP - 403
JO - Faraday Discussions
JF - Faraday Discussions
SN - 1364-5498
ER -