. Author manuscript; available in PMC: 2015 Oct 21.

Published in final edited form as: Phys Chem Chem Phys. 2014 Feb 17;16(21):10112–10128. doi: 10.1039/c3cp54724h

Table 4.

Anharmonic vibrational frequencies (cm⁻¹) of hydrogen-bonded and stacked uracil dimer, computed using B3LYP, B3LYP-D3 and B3LYP-DCP approaches, and corresponding shifts with respect to the isolated molecule (Δ).

B3LYP		B3LYP-D3		B3LYP-DCP		Assignment^a

anharm	Δ	anharm	Δ	anharm	Δ
hydrogen-bonded uracil dimer

3002	*−424.6, −470.4*	2926	*−503.1, −546.4*	2947	*−482.0, −527.5*	νN₃H (M1), νN₁H (M2)
2897	*−530.0, −575.8*	2870	*−559.7, −546.4*	2880	*−549.4, −594.9*	νN₃H (M1), νN₁H (M2)
1700	*−49.9*	1699	*−49.4*	1735	*−38.4*	νC₂=O, νC₄=O, δNH (M2)
1679	*−70.8*	1676	*−72.4*	1715	*−58.1*	νC₄=O, ν ring, δN3H (M1)
1511	*48.6*	1515	*52.3*	1535	*42.3*	δN₁H (M2)
1474	*102.0*	1475	*104.9*	1514	*95.4*	ν ring, δN₁H, δN₃H (M1)
543	*156.1*	543	*155.8*	558	*162.1*	δC=O, δ ring (M2), δ ring (M1)
527	*140.0*	527	*139.9*	539	*143.2*	δC=O, δ ring (M1), δ ring (M2)

stacked uracil dimer

		3362	*−111.1*	3465	−9.6	νN₁H (M1, M2)
		3374	*−98.5*	3465	−9.5	νN₁H (M1, M2)
		1727	−21.6	1745	−27.9	νC₄=O (M1, M2)
		1689	*−59.3*	1734	−39.2	νC₄=O (M1, M2)
		700	*59.1*	687	7.9	γN₃H (M1, M2)
		686	*44.9*	690	11.1	γN₃H (M1, M2)
		824	*296.1*	587	10.4	γN₁H (M1, M2)
		651	*123.7*	584	7.5	γN₁H (M1, M2)

Abbreviations: ν = stretching; δ = in-plane bending; γ = out-of-plane bending; τ = torsional; sciss = scissoring; rock = rocking; wagg = wagging; asym = asymmetric; sym = symmetric; M1 = Monomer 1; M2 = Monomer 2.