We study the dynamics of scattering of two positive polarons moving toward each other with parallel spins and of a polaron and a bipolaron both with positive charges and different velocities, in single chains of cis-polyacetylene and polyparaphenylene. We use the Su−Schrieffer−Heeger model with Hubbard extensions solved within of the time-dependent Hartree−Fock approximation to account for electron−electron interactions, developed over a hexagonal lattice. The main results are elastic scattering in most cases. This behavior changes to transmission of the polaron through the bipolaron when the ratio of their velocities in the same direction is in the range of 3:1 to 5:1 when no external electric field is present. The velocities ratio changes to of 6:1 to 8:1 under external electric field. This suggests that these systems may present an abrupt increase in the charge transport, under specific conditions, in an otherwise smoothly and monotonically increasing relation to the applied field. Their effective masses in these systems are also determined: the polaron effective mass is 4−8 times the rest mass of a free electron, and that of the bipolaron is 15−30 times the electron mass.

Polyparaphenylene is the prototypical conjugated polymer containing phenyl rings and its properties are good references for a family of derived polymers. We investigate the structure, stability, and dynamics of polarons and bipolarons in polyparaphenylene chains under an applied electric field. To do this, we use a bidimensional SSH Hamiltonian model with the Hubbard extension, i.e., with local and nearest-neighbor Coulomb interaction, which has been designed to work with general hexagonal lattices, from which polyparaphenylene can be seen as a prominent case. Using the time-dependent Hartree-Fock approximation, we calculate the structural characteristics, the maximum field strength, supported before polarons and bipolarons gets unstable, and the maximum velocity achieved by these charge carriers. We obtained the polaron and bipolaron terminal velocity to be 0.51 Å/fs and 1.15 Å/fs, respectively. The maximum field strength determined by our calculations is 0.54 mV/Å and 0.80 mV/Å, respectively. Our results are in good agreement with other theoretical methods and experiments.

Conducting polymers based technology has been evolving in several application fields, like opto-electronics, energy conversions and storage, sensors and actuators for mechanical and biological devices and others [1-6]. Detailed phenomenological comprehension of the dynamics of polarons and bipolarons, which are the charge carriers in these material, can improve the design and development of new applications.

Nesta dissertação apresentamos duas vertentes da pesquisa em aprendizagem computacional, uma formal e outra empírica, destacando o modelo de análise "ProuaueZmente 4proàmadamenÉe Coreto" rP,409 e o algoritmo RE.4Z de indução de árvores de decisão sobre atributos de domínio real.A seguir, levantamos a curva de aprendizagem do algoritmo REAL sobre uma base de dados padrão para testes de algoritmos de aprendizagem desta natureza e compa-ramos esta curva com as previsões teóricas dadas pelo modelo PARI e pelo modelo de Convergência Uniforme.Fica evidente a grande lacuna entre estes resultados e então propomos algumas possibilidades de aprofundamento desta análise.