The user documentation for Hibridon
BASISTYPE = 15
System subroutine: sydiat2p
Basis subroutine: hiba15_diat2p.F90
Ref. M.-L. Dubernet and J. M. Hutson, J. Chem. Phys. 101, 1939 (1994).
NTERM (the number of potential surfaces involved: this should be 3 in this case). This parameter can not be changed