# Differences between Gaussian and Slater functions on the quality of the results?

Given two computational programs, one using a Gaussian basis, and the other using Slater basis, what are the practical differences, advantages and disadvantages for each choice ?

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Advantage of the Gaussian basis is that you can use the Gaussian Product Theorem to simplify the two electron integrals at different centers. However, Gaussians ($e^{-\alpha r^2}$) don't capture the cusp of the wavefunction nor the exponential decay ($e^{-r}$) naturally, so one needs more Gaussians for the given accuracy.
Advantage of the Slater type orbitals (STO) $r^n e^{-\zeta r}$ is that they capture both the cusp and the exponential decay, but the disadvantage is that it is harder to calculate the two electron integrals at different centers (for atomic calculations this isn't a problem and so many atomic codes use STO).