Table 1.

Bonding analyses and populations for adenine—thymine (AT) and its smaller analogs.^[a]

	AT	AT′	AT′′	A′T	A′T′	A′T“	A”T	A“T′	A”T“
Bond energy [kcal mol−1]
ΔE	−16.7	−16.4	−15.2	−16.4	−16.0	−15.2	−16.2	−16.8	−16.1
ΔEprep	1.8	2.0	1.4	1.8	1.9	1.5	2.3	2.5	1.8
ΔEint	−18.5	−18.4	−16.7	−18.3	−17.9	−16.7	−18.5	−19.4	−17.9
Bond energy decomposition [kcal mol−1]
ΔEPauli	39.9	39.4	32.0	38.6	37.9	31.3	38.2	38.2	32.3
ΔVelstat	−31.9	−31.2	−27.3	−31.0	−30.0	−26.8	−31.2	−31.5	−28.4
ΔEdisp	−5.4	−5.0	−3.9	−5.3	−4.9	−3.9	−4.1	−3.8	−3.4
ΔEoi	−21.1	−21.6	−17.5	−20.5	−20.8	−17.2	−21.5	−22.2	−18.5
ΔEσ	−19.5	−20.0	−15.9	−19.0	−19.3	−15.6	−19.7	−20.4	−16.6
ΔEπ	−1.6	−1.6	−1.6	−1.5	−1.6	−1.6	−1.8	−1.9	−1.9
Gross populations of A [e−]
σLUMO+1	0.01	0.01	0.01	0.01	0.01	0.02	0.02	0.02	0.02
σLUMO	0.01	0.01	0.02	0.02	0.01	0.02	0.01	0.01	0.01
σHOMO	1.95	1.95	1.97	1.96	1.95	1.97	1.88	1.87	1.91
σHOMO−1	1.97	1.97	1.98	1.96	1.96	1.98	2.00	2.00	2.00
Gross populations of T [e−]
σLUMO+1	0.04	0.00	0.03	0.03	0.01	0.03	0.06	0.01	0.04
σLUMO	0.01	0.08	0.02	0.01	0.08	0.02	0.01	0.10	0.03
σHOMO	1.97	1.98	1.95	1.97	1.98	1.95	1.97	1.98	1.95
σHOMO−1	1.99	1.97	2.00	1.99	1.97	2.00	1.99	1.98	2.00

[a] Energies and geometries computed at BLYP-D3(BJ)/TZ2P in C_s symmetry for the pair and C₁ for monomer.