Potential Energy Surfaces Using Algebraic Methods Based on Unitary Groups

Table 2

Force constants for CO₂ by means of (a) [68] (𝑄𝑀^∗), (b) using the quantum mechanical connection (QM) given by (110), (c) the coherent states method (CS) using (103), (d) the coherent state approach taking the harmonic limit 𝑁→∞, and (e) the coherent states approach using the Hamiltonian (81), but estimated through the connection with the Hamiltonian (110) (CS-PB).

Force constant	QM^∗	QM	CS	CS(𝑁→∞)	CS-PB
𝑓𝑟𝑟aJÅ^(−2)	15.55	17.48	13.32	13.58	17.48
𝑓𝑟𝑟′aJÅ^(−2)	1.86	6.48	−3.46	−3.51	6.48