Knowledge Bank

A variational multiple perturbation method has been developed for the determination of the rotational constant and centrifugal distortion constant of an atom-linear molecule system with a double-minimum potential, given parameters for its potential energy surface. Within the Hamiltonian H, $H=-h2\partial 22\mu \partial R2+h2(J-j)22\mu R2+boj2+V(R.\Theta )$ the potential energy $V(R,\Theta )$ is written $V(R,\Theta )=V1(R,\Theta )+V2(R,\Theta )$ where each $V1(R,\Theta )$ has a single minimum. The eigenfunctions $\varphi 1$ and $\varphi 2$, corresponding to the solution of the zeroth-order problem with $V(R,\Theta )$ replaced by $V1$ and $V2,$ respectively, comprise the terms in the variational zeroth-order wavefunction $\varphi o$, i.e., $\varphi o=a1\varphi 1+a2\varphi 2$ Multiple perturbation theory is then carried out to fourth order to determine the spectroscopic constants. This model is then used to treat ArHCN to test the possibility that ArHCN may have a double-minimum potential.