Bond flexing, twisting, anharmonicity and responsivity for the infrared-active modes of benzene

摘要

In this investigation we have used next generation QTAIM to fully quantity the response to the four infrared (IR)-active modes of all the bonding in benzene. This has been undertaken in terms of bond-flexing, bond-torsion and bond-anharmonicity and the tendencies toward IR-responsivity and IR-non-responsivity. Bond-anharmonicity was not present for the C-C bonds of the lowest frequency mode (721.57 cm(-1)) measured as the absence of relative sliding of the bond critical point (BCP) along the containing bond-path. Additionally, bond-flexing and bond-anharmonicity were absent for this mode by the variation of the wrapping (torsion) of the {p,p '} path-packet, referred to as the Precession K, along the bond-path. The remaining three IR-active mode possessed step-like and variations in the K profiles and displayed anharmonic character. The presence of non-nuclear attractors was detected for the IR-active mode with frequency 1573.93 cm(-1) with C-C K profiles that most closely resemble those of the relaxed benzene.