(a) Calculate the fraction of atom sites that are vacant for copper (Cu) at its melting temperature of 1084C (1357 K). Assume an energy for vacancy formation of 0.90 eV/atom.

I do not understand how the answer gives 4.56*10^-4 when I do the calculation it gives me a whole different number. Am I missing something?

Calculate the fraction of vacancies for copper. NNv=exp(kTQv) Substitute 0.9eV/ atom for Qv,8.62105eV/ atom- K for k, and 1357K for T. NNv=exp((8.62105eV/atom-K)(1357K)0.9eV/atom)NNv=0.000456NNv=4.56104