All electrons within the energy level have the same energy. This idea is modified and developed through introducing students to orbitals. Each atomic energy level contains a number of orbitals. An ...

It allows one to obtain near-exact energies in active spaces containing hundreds of orbitals at a cost that is often orders of magnitude lower than competing methods. Our efforts in this area (along ...

When atoms are put together to form a three-dimensional substance, the properties of the substance are governed by how quantum clouds of electrons, the orbitals, move around and interact with each ...

A further quandry arises when we examine the ionisation energies of the d-block elements. We find that it is the 4s orbital electrons that are ionised first before the 3d orbitals. We have to conclude ...