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The exciton binding energy ([E.sub.b]) and the band gap energy ([E.sub.g]) of poly(phenylene vinylene) are determined by high-resolution measurements of the photoconductivity excitation profile as a function of light polarization, applied electric field, and temperature. At high applied electric fields, a peak in the photoconductivity is observed when the sample is pumped at a photon energy just below the onset of the band-to-band [pi]-[pi] * absorption. This peak is interpreted as resulting from field ionization of a weakly bound exciton with [E.sub.b] [approximately equal to] 60 meV. The binding energy is obtained from the energy of the exciton peak relative to the band edge and independently from analysis of the dependence of the exciton dissociation on field and temperature.

The binding energy obtained from interaction with the nucleotide domain of the coenzyme A (CoA), expressed in the transition states and the enzyme coenzyme A (E-CoA) contributes to catalysis by CoA transferase. Binding to the nucleotide domain of CoA at the active site gives -2.2 kcal/mol of binding energy to stabilize the monocovalent complexes with the enzyme. Binding to the pantoic acid domain helps in the speedy formation of E-CoA.

An analysis of the nature of ligand-protein complexation includes the computation of binding free energy of association facilitated by free energy perturbation methods characteristic of molecular dynamics. The magnitude of the binding free energy, predicted to be of the order of 20 kilocalories per mole, fluctuates between 20 and 22 kcal per mole for five different protocols derived for the ligand, biotin. The binding of biotin to streptavidin is characterized by a negative binding free energy attributed to dispersion effects due to the attractive potential of van der Waals.

The one-electron oxidation potentials, p[K.sub.a] values, and bond dissociation energies of 118 important p- and o-dihydroquinones in DMSO are predicted by using DFT method and the PCM cluster continuum model. The studies have shown that all the five thermodynamic parameters have correlated well with the Hammett substituent parameters, indicating that the thermodynamic parameters are obtained as long as the structure of the hydroquinones is known.

A novel naphthoquinoid singlet biradical stabilized by phenalenyl rings is prepared by a multistep procedure and is examined in terms of covalent bonding interactions. The optical behavior and the magnetic susceptibility measurements have shown that the intermolecular covalent bonding interaction in the 1D chain of naphthoquinoid singlet biradical is greater in strength than the intramolecular one, despite the fact that a fully conjugated Kekule structure can be drawn for naphthoquinoid singlet biradical.

Stabilization energies (S[E.sub.H]) of carbon radicals are defined as the difference between the bond dissociation energy (BDE) of C[H.sub.3]-H, as a reference point, and of R-H, where stabilization energy has implied that it is an intrinsic property of the radical and a quantitative measure of stability. S[E.sub.H] values are neither an intrinsic property nor a quantitative measure of stability and an alternative is available that is not limited only to carbon-carbon and carbon-hydrogen bonds, does not depend on any one particular molecule or BDE as reference point and is accurate with different types of bonds.

Several molecular dynamics and docking simulations are conducted to explain the binding behaviour of the dynamic structures of papain. The binding stability of the compounds is shown to be highly affected by the presence of the flexible residues.

The geometries, energies, and electronic properties of the configurations of Meisenheimer-Wheland (M-W) complexes of sym-triaminobenzenes and 4,6-dinitrobenzofuroxan (DNBF) are examined by using DFT methods. Quantum theory of atoms in molecules (QTAIM) analysis has helped in understanding the nature of the intermonomer interactions and charge transfer and [sigma] bonding is considered for the stability and large binding energies of the M-W complexes.

Several studies are conducted to explain the various electrical properties of the nanoscale vertical interconnect structures (vias) made from chemical vapor deposited carbon. The formation of several such vias and wires is also discussed.

The binding energy and electronic coupling of perylenediimide (PDI) [pi]-stacked dimers are calculated by using M06-2X/6-31++G** as a function of stacking geometry. The strategy of side-by-side comparison of binding energy and electronic coupling is useful for other [pi]-stacked organic thin film transistors (OTFTs) such as pentacene and poly(thiophene) derivatives.

Density functional theory (DFT) is used for examining 132 binary-alloyed nanoparticle systems and their segregation energies are explored to determine core-shell preferences. A universal description is provided for core-shell preference via tight-binding theory that has reproduced the DFT segregation energies and has confirmed the electronic origins and correlations for core-shell behavior.

The properties of an exciton bound to a neutral donor ([D.sup.0],X) in a parabolic GaAs quantum-well wire in the presence of a parallel magnetic field are examined by using the finite-difference method within the quasi-one-dimensional effective potential model. The results have shown that high magnetic fields have increased the binding energy of the [D.sup.0],X in the case of weak spatial confinement.

Threshold collision-induced dissociation techniques are utilized to determine the activation energies (AEs) and bond dissociation energies (BDEs) of metal cation-triethyl phosphate complexes, M(+)(TEP), where M(+) = Mg(+), Al(+), Cu(+), and Zn(+). The results provide insight into the loss of ethene, [C.sub.2][H.sub.4] due to activated dissociation which corresponded to the primary and lowest energy pathway for all four systems.

A density functional theory study of the energetics of isolated [Au.sub.n.sup.+] (n = 5-10) and [Au.sub.n.sup.-] (n = 8?13) gold clusters are presented. The stronger tendency exhibited by the meta-generalized gradient approximation (MGGA) toward 3D structures are found to originate from their smaller gradient enhancement.

The product ratios are studied from the reductive cleavage of di-4-tolylethylsulfonium and di-4-tolyl-2-phenylethylsulfonium salts by a variety of one-electron reducing agents ranging in potential from -0.77 to +2.5 eV and including thermal reductants, indirect electrolyses mediated by a series of cyanoaromatics and excited singlet states. The differences between reductive cleavages of mono- and diarylsulfonium salts are direct consequences of the structures of the sulfuranyl radical intermediates and the bond dissociation energies of the alkyl and aryl bonds.

The size-dependent formation enthalpies of Sn and SnTe nanoclusters are examined by using a nanothermodynamic model based on the liquid-droplet model (LDM) and the modified broken-bond theory. The results have shown that the formation enthalpy has increased with decreasing cluster size and the size-independent surface energy and surface/volume ratio has shown that the model has a better applicability than LDM.