ELECTRON SOLVATION IN METHANE AND ETHANE

The solvation of excess electrons in fluid methane and ethane is studi ed by path integral Monte Carlo computer simulation and by the fast-Fo urier-transform-Lanczos diagonalization method using a newly developed electron-alkane pseudopotential. Many-body polarization interactions between solvent molecules are treated using a mean field approximation in the simulation. In methane, it is found that the electron is in an extended state throughout the whole fluid density range studied. In e thane, it is found that the solvated electron gradually becomes locali zed or ''self-trapped,'' with cavity formation occurring at a fluid de nsity where experimentally the electron is found to have a very low mo bility and the threshold value for electron photoconduction rises abov e zero. The electronic ground state energies in the unperturbed solven t and in the electron-equilibrated solvent were compared. At the same density these electronic energies are very close to each other in meth ane and in the low density ethane fluids, but at higher ethane densiti es, where cavity formation takes place, the ground state energy in the electron solvated fluid is lower than that in the unperturbed fluid.