TY - JOUR AU - Kashirina, N. I. PY - 2018/10/28 Y2 - 2024/03/29 TI - Application of Quantum Field Theory Methods to the Development of the Translational-Invariant Polaron and Bipolaron Theory JF - Ukrainian Journal of Physics JA - Ukr. J. Phys. VL - 59 IS - 11 SE - Solid matter DO - 10.15407/ujpe59.11.1088 UR - https://ujp.bitp.kiev.ua/index.php/ujp/article/view/2018551 SP - 1088 AB - <p>The polaron and bipolaron energy functionals obtained in the framework of quantum field theory have been studied. Exact analytical expressions for the effective functionals are derived in terms of the two-parametrical trial function for a polaron and the three-parametrical one for a bipolaron. Variational solutions are found for the energies of the systems under study in the case of the intermediate values of Fr¨ohlich electron-phonon coupling constant, 4 ≤&nbsp;a ≤20.</p> ER -