momentum $\vec{l}$ to yield the total angular momentum $\vec{J}$. Under spatial inversion $I$, the basis functions  obey the eigenvalue equation, $$\begin{aligned}
I \phi^{JM\varepsilon_I}_{vjl} = \varepsilon_I \phi^{JM\varepsilon_I}_{vjl} ,
%= (-1)^{j_1+j_2+l} \phi^{JM\varepsilon_I}_{vjl}.\end{aligned}$$ with $\varepsilon_I  = (-1)^{j_1+j_2+l} = \pm 1$. Substitution of Eq.  and Eq.  in the time-independent Schr[ö]{}dinger equation $H \Psi = E \Psi$ leads to a set of close-coupling equations in the radial coordinate, $R$. The coupled equations become $$\begin{gathered}
\left\{ - \frac{\hbar^2}{2 \mu} \frac{d^2}{d R^2} +
\frac{\hbar^2 l(l+1)}{2 \mu R^2} 
+ \varepsilon_{vj} - E \right\}
\ F_{vjl}^{JM\varepsilon_I}(R)  \\
+ \sum_{v'j'l'}
  {\cal U}^{JM\varepsilon_I}_{vjl,v'j'l'}(R)
\ F_{v'j'l'}^{JM\varepsilon_I}(R) = 0,
\label{CC1}\end{gathered}$$ where $\mu$ is the reduced mass of the molecule - molecule system. The total energy is $E=\varepsilon_{vj}+E_c$ where $\varepsilon_{vj} = \varepsilon_{v_1j_1} + \varepsilon_{v_2j_2}$ is the rovibrational energy of the two separated molecular fragments and $E_c$ is the collision energy. The interaction potential matrix is given by $$\begin{aligned}
{\cal U}^{JM\varepsilon_I}_{vjl,v'j'l'}(R) = 
\sum_{\lambda} B^{\lambda}_{vj_1j_2,v'j'_1j'_2}(R) f^{J;\lambda}_{jl,j'l'} . \end{aligned}$$ The radial interaction potential term $B^{\lambda}_{vj_1j_2,v'j'_1j'_2}(R)$ is given by $$\begin{gathered}
B^{\lambda}_{vj_1j_2,v'j'_1j'_2}(R) =
\int_0^{\infty} \int_0^{\infty} \chi_{vj_1j_2}(r_1,r_2)  \\
A_{\lambda}(r_1,r_2,R)  \chi_{v'j'_1j'_2}(r_1,r_2) dr_1 dr_2  ,\end{gathered}$$ and the function $f^{J;\lambda}_{jl,j'l'}$ is given in terms of $3-j$, $6-j$, and $9-j$ symbols by $$\begin{gathered}
f^{J;\lambda}_{jl,j'l'} = 
(4\pi)^{-3/2} (-1)^{j_1+j_2+j'_{12}+J}[\lambda,j,l,j',l',\lambda_{12}]^{1/2} \\
\left( \begin{array}{ccc} j_1 & j'_1 & 