Orbitals of atoms other than hydrogen

The starting point for the calculation of wavefunctions for other atoms is generally to assume that each electron is in an orbital like the hydrogen orbitals. Such orbitals are known as atomic orbitals. 

You will probably be aware in describing electronic configurations of atoms, that two electrons could occupy the Is level. 

In the same way, when building up the atomic wavefunction, we assign up to two electrons of opposite spin to each orbital. 

We assign electrons to atomic orbitals starting from the lowest energy orbital. Two electrons, of opposite spin, can go into each orbital and, where there are two or more 

Boundary surfaces for Is, 2s, 2p, 3s, 3p and 3d orbitals with colour indicating relative phases. 0  

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Orbitals of atoms other than hydrogen have the same directional properties corresponding to s, p, d..., but the variation of the orbital with distance from the nucleus differs. 

Clearly, we need to be able to construct Gaussian approximations to the atomic orbitals of atoms other than hydrogen. For applications in molecular orbital theory, we need, in addition, to make allowance for the evident fact that an atom in a molecule is in a different environment to the isolated atom in free space, since any other atoms in a molecule give rise to extra potentials disturbing the free space electron distribution for that atom. 

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