Effects of Electron Screening on Electron Capture Rates in High Density Presupernova Core

Considering that the electron capture rate can be greatly reduced by the electron screening effect in the regime of high temperature and high density, we calculate the effect of electron screening on the electron capture rate for two important elements ⁵⁶Ni and ⁵⁵Co in the high density condition of a pre-supernova star. The effect of electron screening is so effective that the electron capture rate may be reduced to about 20%.