Observed and calculated modes of polythiophene. A complete list of the calculated transition energies with more detailed description is given in Table S1 of the ESI.

Observeda/cm−1			CASTEPb/cm−1		Description
Infrared	Raman	INS	Averagec	Ranged
58 w					Translation
		72 w			Translation
100 w		100 br, m			Translation/libration
		185 w	189	0	Inter-ring in-plane deformation
	293 vw	293 w	286	0	Inter-ring in-plane deformation
		386 w	395	0	Inter-ring in-plane deformation
456 m		458 w	440	5	Intra-ring torsion
		509 w	517	1	Inter-ring in-plane deformation
		558 w	555	9	Intra-ring torsion
584 w		585 m	584	0	Inter-ring in-plane deformation
701 m	701 vw	692 m	695	3	Intra-ring in-plane deformation
737 vw		735 m	727	2	Intra-ring in-plane deformation
786 s		799 s	780	12	Out-of-plane C–H bend
830 m			836	1	Intra-ring in-plane deformation
		876 s	871	5	Out-of-plane C–H bend
1044 w, 1070 w	1047 vw	1055 m	1075	13	In-plane C–H bend
		1200 m	1167	2	In-plane C–H bend
	1368 vw	1372 w	1382	1	Ring stretch
1425 vw, 1439 w		1430 w	1455	1	Ring stretch
	1456 vs	1451 w			Ring stretch
3047 sh					C–H stretch
3061 w					C–H stretch
3074 w					C–H stretch

^a s = strong, m = medium, w = weak, br = broad, sh = shoulder, v = very.

^bTransition energies at the Γ-point of the complete unit cell containing two chains.

^cAverage of the factor group split transition energies at the Γ-point.

^dDifference between the highest and lowest transition energy of the factor group at the Γ-point.