NOPR Collection:

What one can expect from the research performed on highly conducting polymers

Wed, 01 Jun 1994 00:00:00 GMT

Title: What one can expect from the research performed on highly conducting polymers Authors: Ladik, Janos J Abstract: In this introductory paper the practical importance of the experimental and theoretical research on highly conducting polymers is considered. Further, the results of ab initio Hartree-Fock crystal orbital calculations (in some cases corrected also for correlation) on doped and on highly conducting polymers with small gaps (possibility of intrinsic conduction) are reviewed. The theoretical possibilities of improving these band structure calculations to a great extent (good basis set + correlation corrections) due to recent developments in programming are outlined. Finally, the possibilities of using these improved band structures for calculation of electron-phonon interactions (mobility) for soliton and bipolaron studies in these systems and for computing their Auger- and exciton spectra are pointed out. It is concluded that these theoretical developments will lead, within a few years, to the design of new highly conducting polymers with other optimal physical properties ("tailor made polymers") which are necessary to increase their practical applicability to a large extent. Page(s): 449-452

Conducting polymers-Physical concepts and practical applications

Wed, 01 Jun 1994 00:00:00 GMT

Title: Conducting polymers-Physical concepts and practical applications Authors: Roth, Siegmar Abstract: Developments in different fields of applications of conducting polymers, e.g., electrical conductivity, luminescence and non-linear optics, localisation and large scale electronics are discussed. The paper summarises the experience accumulated in the Network NEOME, a network of the European Materials Research Society. Page(s): 453-460

The Pariser-Parr-Pople model for trans-polyenes-Ill: Derivation of equations of motion for excited state dynamics using two-determinantal and MCSCF type electronic wave functions

Wed, 01 Jun 1994 00:00:00 GMT

Title: The Pariser-Parr-Pople model for trans-polyenes-Ill: Derivation of equations of motion for excited state dynamics using two-determinantal and MCSCF type electronic wave functions Authors: Forner, Wolfgang Abstract: An SCF treatment for excited two-determinantal states and for multiconfiguration SCF (MCSCF), including single excitations within the framework of the semiempirical Pariser-Parr-Pople (PPP) Hamiltonian is derived. It is shown how analytical gradients of the electronic energy with respect to the geometrical variables can be calculated and the formalism for the two-determinantal state is applied to the dynamics of singlet and triplet excited Bu states of polyenes. It is shown that due to technical difficulties concerning orbital ordering the inclusion of all single excitations in the excited state wave functions via an MCSCF treatment is necessary. The use of an MCSCF procedure is important because in a CI treatment the gradients of the energy needed for the time simulations cannot be computed analytically. The necessary equations are derived. Page(s): 461-479

Strategies for the theoretical design of new materials in solid state physics and their applications

Wed, 01 Jun 1994 00:00:00 GMT

Title: Strategies for the theoretical design of new materials in solid state physics and their applications Authors: Otto, P Abstract: Chemical engineering in material sciences is nowadays one of the most important challenges. It requires a combined application of experimental and theoretical methods. On one side, theoretical investigations may help in understanding chemical and physical phenomena. On the other side, calculations on compounds not yet synthesized but of potential technical interest, showing a combination of selected properties, are less expensive than experiments and may give hints on how to proceed further in the experimental work. It is necessary in this context to develop theories and mathematical algorithms to achieve the required goal. To perform calculations accurate enough for reliable conclusions, the most powerful computer systems available have to be used. It is the general opinion that development of massively parallel multiprocessor systems is the most promising way at present in the near future. As a consequence, users have to adjust their computer programs to the new architectures in order to use the complete capacity of the machines. In this work we demonstrate discuss different steps involved in the search of low-gap polymers with high nonlinear optical properties using efficiently adapted programs. Page(s): 480-488