Millimeterwave Spectral Studies of Propynal (HCCCHO) Produced by DC Glow Discharge and Ab Initio DFT Calculation

Table 2

Ground-state rotational and centrifugal distortion constants of propynal (HCCHO).

Constants	“Global” fit using microwave and millimeterwave data	Reference [6]	DFT calculation
A (MHz)	68035.251±0.021	68035.299±0.043	69124.41
𝐵 (MHz)	4826.224±0.001	4826.3014±0.0073	4816.87
𝐶 (MHz)	4499.588±0.001	4499.5107±0.0069	4495.94
𝐷𝐽 (kHz)	1.868±0.001	1.917±0.012	1.764
𝐷𝐽𝐾 (kHz)	−147.757±0.030	−148.102±0.047	−127.969
𝐷𝐾 (kHz)	8978.402±5.58	8991.240±9.73	8110.126
𝑑1 (kHz)	−0.353±0.004	0.3458±0.0014	−0.315
𝑑2 (kHz)	−0.022±0.002	−19.500±1.59	−0.018
𝐻𝐽𝐾 (Hz)	−0.659±0.047	−0.741±0.059
𝐻𝐾𝐽 (Hz)	−8.336±0.125	−8.310±0.130
ℎ1 (Hz)	0.0120±0.007	—
𝜎^b	0.0814	0.08721
𝜅^c	−0.989	−0.989
Δ^d	0.173	0.177
𝑁^e	145	96

^bStandard deviation of the overall fit.
^cAsymmetry parameter 𝜅=(2𝐵−𝐴−𝐶)/(𝐴−𝐶).
^dInertia defect Δ=𝐼_𝑐−𝐼_𝑏−𝐼_𝑎.
^eNumber of transitions used in the fit.