It is shown that exciton states with various total angular momenta (L = 0, 1, 2, 3) are differently affected by the interaction with LO phonons in polar materials. In particular, a dependence is found of the binding energy on the value of L not expected on the basis of the statically screened electron-hole attraction. Calculations for CuCl and other ionic compounds show that the lowest L = 1 state (n = 2) is less bound than the corresponding exciton state with static screening. This effect, which is opposite to the polaronic effect on the ground state, is still present for L ≧ 2 but it decreases with increasing L. The computed binding energies of 2p excitons compare favorably with the available experimental data. The method is also applied to the calculation of bipolaron binding energies.
Polaronic Effects on Exciton States with Different Angular Momenta
STRINATI CALVANESE, Giancarlo
1989-01-01
Abstract
It is shown that exciton states with various total angular momenta (L = 0, 1, 2, 3) are differently affected by the interaction with LO phonons in polar materials. In particular, a dependence is found of the binding energy on the value of L not expected on the basis of the statically screened electron-hole attraction. Calculations for CuCl and other ionic compounds show that the lowest L = 1 state (n = 2) is less bound than the corresponding exciton state with static screening. This effect, which is opposite to the polaronic effect on the ground state, is still present for L ≧ 2 but it decreases with increasing L. The computed binding energies of 2p excitons compare favorably with the available experimental data. The method is also applied to the calculation of bipolaron binding energies.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
