Table 2.

Comparison of calculated thermodynamic properties as obtained by various methods for BeH, BeH₂, and H₂(D₂) molecules to known experimental values. ∆_f H ^° is in kJ mol^-1, R_e in Å, and ω_e in cm⁻¹. The enthalpy of formation for BeH and its estimation for BeH₂ are taken from ref. [50]. Experimental values for the hydrogen molecule are taken from the NIST-JANAF thermochemical Tables [49]. Spectroscopic values for BeH and BeH₂ are retrieved from ref. [32, 33]. ${\omega }_e^a$ for BeH₂ corresponds to the asymmetric stretching vibration and ${\omega }_e^b$ to the bending vibration

Method		BeH		BeH 2				H 2		D 2
	∆f H °	R e	ω e	∆f H °	R e	${\mathit{\omega }}_{\mathit{e}}^{\mathit{a}}$	${\mathit{\omega }}_{\mathit{e}}^{\mathit{b}}$	R e	ω e	ω e
B3LYP-D	307.86	1.340	2062.4	133.7	1.324	2263.5	724.8	0.742	4415.2	3123.2
B97D	328.60	1.367	1936.8	140.98	1.337	2201.8	706.0	0.744	4373.5	3093.7
B2PLYPD	316.65	1.338	2084.9	144.90	1.323	2278.4	726.8	0.740	4461.2	3155.8
M06	313.34	1.341	2089.0	128.77	1.326	2264.6	705.2	0.744	4423.8	3129.3
G4	331.52	1.344	2064.5	158.93	1.327	2275.6	746.3	0.743	4465.7	3159.0
CCSD(T)	340.23	1.342	2062.4	168.31	1.327	2257.2	717.1	0.742	4401.1	3113.2
Exp.	321 ± 30	1.342	2061.4	125.52	1.326	2255.2	706.3	0.741	4401.2	3115.5