. 2016 Mar 10;144(10):104304. doi: 10.1063/1.4942019

TABLE I.

Optimized CASSCF(18,12) geometries and 1¹A₁ and 2¹A₁ state energies of several points along the 1¹A₁ and 2¹A₁ potential energy surfaces, calculated using the cc-pVTZ and cc-pVQZ basis sets. (Bond lengths and bond angles are given in Å and degrees, respectively. Energies (E) are reported in mh relative to their respective energies at the 1¹A₁ state open minimum.)

	cc-pVTZ Basis set				cc-pVQZ Basis set
Geometry^a	E(1¹A₁)	E(2¹A₁)	R _OO	∠	E(1¹A₁)	E(2¹A₁)	R _OO	∠
OM^b^,^c	0.00^d	150.96	1.292	116.5	0.00^e	152.55	1.288	116.6
RM	47.60	335.13	1.466	60.0	48.86	337.98	1.465	59.9
TS	84.13	84.78	1.424	84.1	85.12	85.96	1.428	84.0
XM	83.42	84.68	1.431	83.8	84.96	85.57	1.428	83.8
CI	87.36	87.61	1.491	83.3	88.85	88.85	1.491	83.3

^{^a}

The following abbreviations are used in this and the following tables: OM = 1¹A₁ state open minimum, RM = 1¹A₁ state ring minimum, TS = 1¹A₁ state transition state, XM = 2¹A₁ state minimum, CI = conical intersection between the 1¹A₁ state and the 2¹A₁ state.

^{^b}

The experimental values of OM for R_OO and ∠ are 1.278 Å and 116.8°, respectively.³⁹

^{^c}

The bond lengths and bond angles that are listed for each geometry were determined from state-averaged CASSCF(18,12) calculations. Single-state CASSCF(18,12) calculations for the 1¹A₁ state for the optimized open minimum geometry yielded R_OO = 1.285 Å and ∠ = 116.7° for the cc-pVTZ basis set and R_OO = 1.281 Å and ∠ = 116.8° for the cc-pVQZ basis set.

^{^d}

The absolute cc-pVTZ energy for this geometry is −224.569 832 hartree.

^{^e}

The absolute cc-pVQZ energy for this geometry is −224.586 929 hartree.