TY - JOUR
T1 - Theoretical study of the radiative lifetime of the a 1Π u, state of C2
AU - Langhoff, Stephen R.
AU - Bauschlicher, Charles W.
AU - Rendell, Alistair P.
AU - Komornicki, Andrew
PY - 1990/6/1
Y1 - 1990/6/1
N2 - We have studied the Phillips (A 1Πu-X 1Σg
+) band system of C2 in order to help resolve the discrepancy between the best theoretical lifetimes and those deduced recently from laser-induced fluorescence (LIF) studies. Our calculated lifetime for the A 1Πu (υ′ = 0, J′ = 1) state is 13.0 μs, in excellent agreement with the recent calculations of ONeil et al., but considerably shorter than the direct experimental measurements. A measure of the accuracy of the complete-active- space self-consistent-field (CASSCF) multireference configuration-interaction (MRCI) results in this work is obtained by a series of calibration calculations. Convergence in the n-particle space is demonstrated by comparison with full configuration interaction calculations in a double-zeta plus polarization basis, while the convergence of the one-particle basis set is demonstrated by systematically expanding the one-particle basis set up through g angular momentum functions. Furthermore, a coupling of the one- and n-particle spaces is shown to be unimportant by systematically expanding the active space in the CASSCF/MRCI treatment. Given that our theoretical results are estimated to be accurate to about 5%, the LIF lifetimes would appear to contain some systematic error.
AB - We have studied the Phillips (A 1Πu-X 1Σg
+) band system of C2 in order to help resolve the discrepancy between the best theoretical lifetimes and those deduced recently from laser-induced fluorescence (LIF) studies. Our calculated lifetime for the A 1Πu (υ′ = 0, J′ = 1) state is 13.0 μs, in excellent agreement with the recent calculations of ONeil et al., but considerably shorter than the direct experimental measurements. A measure of the accuracy of the complete-active- space self-consistent-field (CASSCF) multireference configuration-interaction (MRCI) results in this work is obtained by a series of calibration calculations. Convergence in the n-particle space is demonstrated by comparison with full configuration interaction calculations in a double-zeta plus polarization basis, while the convergence of the one-particle basis set is demonstrated by systematically expanding the one-particle basis set up through g angular momentum functions. Furthermore, a coupling of the one- and n-particle spaces is shown to be unimportant by systematically expanding the active space in the CASSCF/MRCI treatment. Given that our theoretical results are estimated to be accurate to about 5%, the LIF lifetimes would appear to contain some systematic error.
UR - http://www.scopus.com/inward/record.url?scp=36549104404&partnerID=8YFLogxK
U2 - 10.1063/1.458297
DO - 10.1063/1.458297
M3 - Article
AN - SCOPUS:36549104404
VL - 92
SP - 6598
EP - 6603
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
SN - 0021-9606
IS - 11
ER -