Quantization Study Of Intramolecular Interaction And Transition Orbital

In the Chapter 1,it mostly introduces the fundamental background of quantum theory of atoms in molecules(QTAIM)to promote the understanding of the indices.In the Chapter 2,next generation QTAIM was used to explain the structural preferences and differences of a series benzene ester and amide.The planarity of the amide structures was explained by a resistance to torsion of the N-linking bond.Conversely,a resistance to planarity of the O-linking bond in the benzene ester explained the twisted geometries.Hydrogen bonding that linked the aromatic ring with the rest of the molecule was only found to be present for the amide.Confirmation of the findings was provided by a stress tensor analysis.In the Chapter 3,next generation QTAIM was applied to analyze along an entire bond-path,intramolecular interactions known to influence the photo-isomerization dynamics of a light-driven rotary molecular motor.The 3-D bond-path framework set B0,1,constructed from the least and most preferred directions of electronic motion,provided new insights into the bonding leading to different S1 state lifetimes including the first quantification of covalent character of a closed-shell intramolecular bondpath.The research undertook the first use of the stress tensor trajectory T?(s)analysis on selected non-adiabatic molecular dynamics trajectories with the electron densities obtained using the ensemble density functional theory method.The stress tensor T?(s)analysis was found to be well suited to follow the dynamics trajectories that included the S0 and S1 electronic states through the conical intersection and also provided to a new measure to assess the degree of purity of the axial bond rotation for the design of rotary molecular motors.In the Chapter 4,for the first time,the S0?S1(S01)and S0?S2(S02)natural transition orbital(NTO)densities for fulvene,using the 3-D next generation QTAIM that can visualize and quantify the rearrangement of the charge density that occurs in response to the applied torsion and as a consequence of the preferred direction of electron density accumulation.A symmetrization of the position of the bond critical point(BCP)of the torsional C2-C6 BCP along the containing bond-path was determined to be characteristic of the presence of a conical intersection(CI)for the S0?S1(S01)transition.In the chapter 5,summary of this thesis and the future research direction are provided in this part.