Abstract
A first-principles calculation to determine the electronic properties of trans-polyacetylene using Hedin's approximation for the self-energy is described. To our knowledge this work is the first application of the method to a quasi-one-dimensional system. The zeroth-order approximation is used to initialize the calculation with the self-energy described by the Hartree-Fock exchange interaction. To include electron exchange and correlation beyond Hartree Fock, the first-order () approximation for the self-energy is adopted. Now the self-energy is energy dependent and is described by the single-particle Green's function () and the screened Coulomb interaction (). For screening the Coulomb potential the complete wave number and frequency-dependent dielectric response tensor, within the random phase approximation, is employed. The calculation is carried to self-consistency. By implementing the , the Hartree-Fock minimum band gap is reduced by 68% and falls within the experimentally observed range. The optical reflectance and electron-energy-loss function, calculated with local field and lifetime effects, are presented and compared with experiment.
- Received 14 August 1995
DOI:https://doi.org/10.1103/PhysRevB.53.3662
©1996 American Physical Society