## Project Details

### Description

In order to determine the geometrical and electrical properties of polymers, new methodologies (Fourier transform and multiple Taylor expansions) that take into account long-range effects for the Coulomb and exchange interactions have been developped in the laboratory.

Especially, new procedures using multiple Taylor expansions have been developped in order to determine with high accuracy the geometry of stereoregular polymers. The electron correlation calculated with the help of Møller-Plesset, density functional, electron and polarization propagators theories is introduced in the determination of the total energy as well as in the evaluation of electronic excitations. These approaches take adavantage of the translational symmetry and of Bloch's theorem in order to determine the crystalline orbitals. The polymeric approach leads to a decrease of the cpu-time with respect to the long oligomer approach.

Once the ab initio band structures have been evaluated by the self-consistend field approach, many properties can be evaluated:

- The total energy as a function of the helical angle of the polymer
- Density of states which is related to XPS/UPS spectra
- Linear polarizabilities for which one has to solve problems linked to the non-periodicity of the dipole moment operator
- Geometry and unit cell length for which the long-range electrostatic effects are important
- Excitation energies which require the inclusion of electron correlation in order to be accurately estimated

Status | Active |
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Effective start/end date | 1/01/71 → 31/12/22 |

### Keywords

- propagators
- electronic structure
- spectroscopies
- polarizabilities
- polymers
- electron correlation
- Fourier transform
- density of states