semiempirical binding energy--coulomb approximation

Apr 2018
3
1
Hi,

I've been stuck on this one thing in my textbook. For the coulomb approximation--as part of the semiempirical binding energy formula--it is given as:

B<coul>=-a<coul>Z^2/A^(1/3)

where:

a<coul>=3/5*ke^2/R<0>

The issue that I'm having is that the book and also online sources site the couloumb constant (a<coul>) as 0.711MeV-0.807MeV.

With the constants from the textbook:
k=9E9 [Nm^2/C^2]
e=1.6E-19 [C]
R<0>=1.07 [fm]

I don't get a value near 0.711 MeV, more like 129feV. The only way I get 0.807MeV is if I plug in the numbers as:

3/5*ke/R<0>

without the charge squared.

Could someone help me understand what I'm doing wrong?