A Bond Charge Model Ansatz for Intrinsic Bond Energies: Application to C-C Bonds

A simple Bond Charge Model is proposed to predict <i>intrinsic</i> bond energies. Model parameters can be derived from the topology of the Electron Localization Function and optimized geometries through classic considerations. Results for carbon-carbon covalent bonds are shown to be very accurate in different chemical environments. Insight can be extracted from the application of the model due to its elementary construction and simple mathematical formulation. The remarkable robustness of the fitted model highlights how different Density Functional Approximations relate geometries, densities and energies.

A Bond Charge Model Ansatz for Intrinsic Bond Energies: Application to C-C Bonds

A simple Bond Charge Model is proposed to predict <i>intrinsic</i> bond energies. Model parameters can be derived from the topology of the Electron Localization Function and optimized geometries through classic considerations. Results for carbon-carbon covalent bonds are shown to be very accurate in different chemical environments. Insight can be extracted from the application of the model due to its elementary construction and simple mathematical formulation. The remarkable robustness of the fitted model highlights how different Density Functional Approximations relate geometries, densities and energies.

Theory of phonon conductivity of semiconductor superlattices

ABSTRACTWe present a single-mode relaxation-time theory of phonon conductivity of semisonductor superlattices with nanoscale periodicities. Analytic expressions have been obtained for phonon-interface scattering and phonon-phonon scattering taking into consideration the effects of interfaces and the presence of two materials in superlattices. Numerical calculations have been performed by using phonon eigensolutions obtained from an enhanced adiabatic bond charge model and by carrying out Brillouin zone integration using the special q-points scheme. The experimental measured conductivity results for Si(19)/Ge(5) and Si(72)/Ge(30) superlattices have been successfully explained.