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A novel intraline of conical intersections for methylamine: A theoretical study
Author(s) -
Levi C.,
Halász G. J.,
Vibók Á.,
Bar I.,
Zeiri Y.,
Kosloff R.,
Baer M.
Publication year - 2008
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.21940
Subject(s) - conical intersection , methylamine , line (geometry) , degeneracy (biology) , physics , conical surface , adiabatic process , plane (geometry) , quantum mechanics , dipole , gravitational singularity , potential energy , chemistry , geometry , mathematics , bioinformatics , organic chemistry , biology
In this article the study of conical intersections (ci) related to the NH bond in the methylamine, CH 3 NH 2 , molecule is extended. In a previous publication (Levi et al., J Chem Phys 2008, 128, 244302) we reported on a novel feature associated with the intersection of the two lowest states 1 A' and 1 A″ of the methylamine. We established the existence of a finite (closed) line of ci located in the HCNHH plane—a line that is formed by moving a single hydrogen on that plane while fixing the (six) other atoms. The validity of this line was proved by studying the singularities of the (angular) nonadiabatic coupling terms (NACT)—a study that was later supported by revealing the degeneracy points formed by the two interacting adiabatic potential energy surfaces (PESs). This situation led to two additional interesting features: (i) Along any (open) contour in the above plane that intersects this line is formed a narrow, spiky NACT for which the area under it is ∼π/2; (ii) In case of a closed contour the corresponding topological (Berry) phase is zero (and not an integer multiple of π as is usually the case). In the current article we present the theory to support these findings. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009