Table 3.

Harmonic frequencies (in cm⁻¹) and intensities (in km mol⁻¹) for cyc-CHC₃${\text{H}}_2^{+}$ computed at different levels of theory.

ω	Sym.	B3/SNSD		PW6/julDZ		B2/junTZ		rDSD/junTZ		TZ/augVTZa	MP2a
		ω	I	ω	I	ω	I	ω	I	ω	I
ω1	a1	3,366	175.49	3,396	182.12	3,387	159.25	3,379	148.18	3370.2	121
ω2	a1	3,310	68.88	3,350	67.03	3,335	70.79	3,333	66.88	3325.9	76
ω3	a1	1,973	52.29	2,000	56.93	1,993	75.71	2,004	98.48	1977.3	186
ω4	a1	1,673	51.24	1,692	48.78	1,695	54.20	1,697	65.58	1681.3	67
ω5	a1	917	2.85	913	3.63	920	4.40	912	6.20	908.2	7
ω6	a1	798	22.40	825	19.42	772	33.55	766	42.04	768.6	63
ω7	a2	758	0.00	747	0.00	749	0.00	735	0.00	713.1	0
ω8	b1	731	65.29	723	63.95	735	65.00	731	64.92	711.5	77
ω9	b1	450	103.33	436	94.32	503	92.13	517	89.33	509.3	12
ω10	b1	361	3.08	323	13.42	382	3.55	376	4.96	355.9	0
ω11	b2	3,245	196.22	3,281	202.93	3,268	210.18	3,265	208.15	3260.5	234
ω12	b2	995	6.38	989	5.47	998	7.00	994	6.38	985.5	8
ω13	b2	944	0.69	933	0.45	937	0.04	935	0.11	920.6	3
ω14	b2	627	28.13	680	32.53	571	25.14	578	26.50	580.4	22
ω15	b2	200	24.47	190	23.01	170	26.96	160	27.56	155.7	46

^aTaken from Westbook et al. (2020).