# Solve this with lower incomplete gamma function

1. Oct 15, 2008

### Alexitron

1. The problem statement, all variables and given/known data
$$\int e^{-\frac{2Zr}{a}}*r^{-1}dr$$ Boundaries:[0,R]

2. Relevant equations

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3. The attempt at a solution
I tried to solve this with lower incomplete gamma function and got $$\gamma$$(0,$$\frac{2ZR}{a}$$) which is infinite i think.
Z=81,a:Bohr radius,R=r0*A^(1/3) ,Th:A=203,r0=1,2*10^(-13)

2. Oct 15, 2008

### CompuChip

Re: Integral

I don't know what the lower incomplete gamma function is, but Mathematica gives me
$$\int_\epsilon^R \frac{1}{r} e^{-2Zr/a} \, \mathrm dr = \gamma(0, 2Z\epsilon/a) - \gamma(0, 2ZR/a)$$
which is finite for $\epsilon > 0$ but diverges for $\epsilon \to 0$.

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