TABLE VII.

CC2 excitation energies computed with the present approach (in eV), the percentage of VNOs and NAFs dropped, and computation times (in min) using the default thresholds with the aug-cc-pVTZ basis set for big molecules.

Molecule	Number of atoms	Number of basis functions	State	Character	${\omega }_{\mathrm{CC2}}$	Dropped VNOs	Dropped NAFs	tCISa	$t_{\overline{\text{𝐉}}}$ b	tCC2c
Flv(a)	51	2001	S1	$\pi \to {\pi }^{*}$	2.750	60.9	82.1	15.5	81.6	3.7
			S2	$\pi \to {\pi }^{*}$	2.995	60.8	82.0		81.6	3.6
			S3	$n,\sigma \to {\pi }^{*}$	3.339	61.1	82.1		81.6	3.4
			S4	$\pi \to {\pi }^{*}$	3.613	60.9	82.0		81.6	3.5
Dyad	53	2051	S1	$\pi \to {\pi }^{*}$	3.063	61.4	82.7	15.4	84.1	3.5
			S2	CT	3.373	61.7	82.8		84.1	3.5
			S3	$\pi \to {\pi }^{*}$	3.506	61.2	82.6		84.1	3.4
			S4	CT	3.826	61.2	82.7		84.1	3.5
Bisimide derivative	60	2346	S1	$\pi \to {\pi }^{*}$	2.543	61.5	82.5	24.6	179.3	7.0
			S2	$\pi \to {\pi }^{*}$	3.438	61.5	82.6		178.7	6.7
			S3	$\pi \to {\pi }^{*}$	3.707	61.5	82.6		179.2	6.4
			S4	$\pi \to {\pi }^{*}$	3.793	61.5	82.6		178.9	6.4
Flv(b)	78	2829	S1	$\pi \to {\pi }^{*}$	2.603	63.8	83.3	53.9	416.3	12.9
			S2	$\pi \to {\pi }^{*}$	2.978	63.9	83.3		416.2	12.9
			S3	$n,\sigma \to {\pi }^{*}$	3.279	64.0	83.4		416.2	13.0
			S4	$\pi \to {\pi }^{*}$	3.329	63.8	83.3		415.9	13.0
D21L6	98	3412	S1	CT	2.622	65.2	84.4	42.8	1093.2	29.1
			S2	$\pi \to {\pi }^{*}$	3.442	65.1	84.3		1092.9	30.0
Average						62.3	82.9
Maximum						65.2	84.4
Minimum						60.8	82.0

^aAverage wall time for a CIS iteration using a multi-state, integral-direct algorithm.

^bAverage wall time for the construction of the $\overline{\text{𝐉}}$ integral list. The calculation of the MP2 density is distributed equally among the excited states, that is, $t_{\overline{\text{𝐉}}}=t_{\mathbf{\text{CIS(D)}}}+t_{\text{𝐌𝐏𝟐}}/n+t_{\text{𝐖}}+t_{\mathrm{Int}}$, where t_CIS(D), t_MP2, and t_W are the wall times required for the evaluation of the CIS(D) and MP2 density matrices and the W matrix, respectively, n stands for the number of excited states, and t_Int is the wall time required for the integral transformations.

^cAverage wall time for a CC2 iteration.