Constructing Potential Energy Surfaces for Polyatomic Systems: Recent Progress and New Problems

Table 4

Eigenvalues of ammonia inversion (in cm⁻¹).

ν 2	EC-2009^a	Exp.^b
0^+	0.00	0.00
0^-	3.64	0.79
1^+	861.39	932.43
1^−	962.90	968.12
2^+	1533.36	1598.47
2^−	1942.29	1822.18

^a[39]; ^b[80].