I am trying to calculate the fourier transform of $$\left(\frac{1}{\sigma \sqrt{2\pi}}\right)^{1/2}e^{\frac{-x^2}{4\sigma^2}}$$
Attempt: $\vert\psi(x) \vert^2 = \frac{1}{\sqrt{2\pi \sigma}}e^{-\frac{x^2}{2\sigma^2}}$
Now $\hat{\psi}(k) = \frac{1}{\sigma2\pi}\int_{\mathbb{R}}e^{ikx}e^{-\frac{x^2}{2\sigma^2}} =\frac{1}{\sigma2\pi}\int_{\mathbb{R}} e^{ikx-\frac{x^2}{2\sigma^2}}$
I don't know how to simplify this into $\delta$ expression.