Table 1.

Bond Energies (D_e) and Adiabatic Excitation Energies (T_e) in eV, and Geometries in Å for the Ground (X) and the First Three Excited States (Denoted as A, C, and D) of LiH^d

propertya	MSDFT	MS-CASPT2	MRCI69	expt22,75
S0, X1Σ+
Re	1.6	1.588	1.589	1.595
De	2.223	2.449	2.522	2.515
LiH → Li+ + H−	7.180			7.151
S1(2p), A1Σ+
Re	2.5	2.249	2.577	2.596
De	0.95	1.05	1.077	1.076
Te	2.92	3.24	3.29	3.288
Tvertb	3.40
S2(3s), C1Σ+
S2(3s), C1Σ+
Re(in)	2.125	2.117	2.023	2.0289
Re(o)	5.0	5.29	5.384	5.3789
R‡	2.5	2.91
$\mathrm{\Delta }{E}_{\mathit{\text{diss}}}^{\ne }$ c	0.12	0.06
De(in)	−0.17	0.14	0.16
De(o)	0.95	1.08	1.15	1.0589
Te(in)	5.88	5.65	5.74
Te(o)	4.78	5.21	4.85	4.8322
S3(3p), D1Σ+
Re(in)	1.9, 2.75	2.1	2.822
Re(o)	10	7.9	10.522
De(in)	0.06	0.25	0.3322
De(o)	0.29	0.24	0.3322
Te(in)	6.0	6.2	5.922
Te(o)	5.7		5.922

^a(in) and (o) specify the inner energy minimum and outer energy minimum, respectively.

^bVertical excitation energy at ground-state equilibrium geometry.

^c $\mathrm{\Delta }{E}_{\mathit{\text{diss}}}^{\ne }$ denotes the barrier higher for dissociation (in eV).

^dThe aug-cc-pVTZ basis set is used in all calculations using the multistate density functional theory (MSDFT) and multistate complete-active-space second-order perturbation theory (MS-CASPT2). The PBE0 density functional is used in MSDFT; the (2,9) active space is employed for MS-CASPT2.