  Search for configuration space with welldefined topological (Berry) phases
corresponding to Jahn Teller (JT) conical intersection (CI) and Renner
Teller(RT) parabolic intersection (PI) in the linear tetra-atomic molecular
system on introduction of bending, reveal the interesting aspect that these
potential intersections may appear in molecular plane as well as out of the
molecular plane. While understanding this aspect is important for following the
class of phenomena led by potential intersections, till date studies on
molecular systems including pairs like (C2H2plus , HCNH) as well as (N2H2plus ,
HBNHplus ), have not been able to clarify the issue. The present paper embodies
calculation of non-adiabatic coupling terms (NACTs) involving four low lying
states of slightly bent HCNOplus , a motivated choice of tetra-atomic with all
four different atoms, to study this aspect associated with JTCI and RTPI in
slightly bent linear system. The plane of appearance of these effects, has been
advocated to be related to electronic configuration of the concerned states of
the molecular system.
