TY - JOUR
T1 - Anharmonic vibrational frequencies and vibrationally-averaged structures of key species in hydrocarbon combustion
T2 - HCO+, HCO, HNO, HOO, HOO-, CH3+, and CH3
AU - Keceli, Murat
AU - Shiozaki, Toru
AU - Yagi, Kiyoshi
AU - Hirata, So
N1 - S.H. expresses his sincere gratitude to Professor Henry F. Schaefer III for the continuous support and encouragement generously extended to the author and also for his leadership in the field. The authors thank Professors T. Daniel Crawford and C. David Sherrill for their invitation to contribute to this Special Issue. This work was supported by US Department of Energy (Grant No. DE-FG02-04ER15621) and the Donors of the American Chemical Society Petroleum Research Fund (Grant No. 48440-AC6).
PY - 2009/1
Y1 - 2009/1
N2 - A general scheme to predict anharmonic vibrational frequencies and vibrationally-averaged structures and rotational constants of molecules is presented with applications to some key species in hydrocarbon combustion (some also of importance in atmospheric and/or interstellar chemistry): HCO+, HCO, HNO, HOO, HOO-,[image omitted], and CH3. A combination of coupled-cluster singles and doubles (CCSD), CCSD with a second-order perturbation correction in the space of triples [CCSD(2)T] and in the space of triples and quadruples [CCSD(2)TQ], and a correlation-consistent basis set series has been employed to achieve the complete-correlation, complete-basis-set limits of the potential energy surfaces (PESs) of these species near equilibrium geometries. A new, compact representation of PESs that combines two existing representations, namely, a fourth-order Taylor expansion and numerical values on a rectilinear grid, has been proposed and shown to yield accurate frequencies, when combined with vibrational general-order configuration-interaction method. The predicted frequencies (and the observed in parentheses, when available) of the fundamentals are as follows: 823 (830), 2175 (2184), and 3083 (3089) cm-1 in HCO+; 1079 (1081), 1874 (1868), 2432 (2434) cm-1 in HCO; 1503 (1501), 1572 (1565), and 2683 (2684) cm-1 in HNO; 1121 (1098), 1399 (1392), and 3447 (3436) cm-1 in HOO; 739, 1088, and 3587 cm-1 in HOO-; 1383 (1359 7), 1384 (1370 7), 2940, and 3096 (3108) cm-1 in [image omitted]; 565 (606), 1377, 3002 (3004), and 3139 (3161) cm-1 in CH3. The mean absolute deviation in the predicted frequencies is 11 cm-1.
AB - A general scheme to predict anharmonic vibrational frequencies and vibrationally-averaged structures and rotational constants of molecules is presented with applications to some key species in hydrocarbon combustion (some also of importance in atmospheric and/or interstellar chemistry): HCO+, HCO, HNO, HOO, HOO-,[image omitted], and CH3. A combination of coupled-cluster singles and doubles (CCSD), CCSD with a second-order perturbation correction in the space of triples [CCSD(2)T] and in the space of triples and quadruples [CCSD(2)TQ], and a correlation-consistent basis set series has been employed to achieve the complete-correlation, complete-basis-set limits of the potential energy surfaces (PESs) of these species near equilibrium geometries. A new, compact representation of PESs that combines two existing representations, namely, a fourth-order Taylor expansion and numerical values on a rectilinear grid, has been proposed and shown to yield accurate frequencies, when combined with vibrational general-order configuration-interaction method. The predicted frequencies (and the observed in parentheses, when available) of the fundamentals are as follows: 823 (830), 2175 (2184), and 3083 (3089) cm-1 in HCO+; 1079 (1081), 1874 (1868), 2432 (2434) cm-1 in HCO; 1503 (1501), 1572 (1565), and 2683 (2684) cm-1 in HNO; 1121 (1098), 1399 (1392), and 3447 (3436) cm-1 in HOO; 739, 1088, and 3587 cm-1 in HOO-; 1383 (1359 7), 1384 (1370 7), 2940, and 3096 (3108) cm-1 in [image omitted]; 565 (606), 1377, 3002 (3004), and 3139 (3161) cm-1 in CH3. The mean absolute deviation in the predicted frequencies is 11 cm-1.
KW - Anharmonicity
KW - Electron correlation
KW - Hydrocarbon combustion
KW - Molecular vibrations
KW - Potential energy surfaces
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U2 - 10.1080/00268970902889626
DO - 10.1080/00268970902889626
M3 - Article
AN - SCOPUS:68249153516
SN - 0026-8976
VL - 107
SP - 1283
EP - 1301
JO - Molecular Physics
JF - Molecular Physics
IS - 8-12
ER -