Helium atom precision measurements and calculations have a history of nearly a century. In the 1960s, theorists discovered that the fine-structure split (23P0-23P2) of the 23P energy level of ...

The helium atom comprises a doubly charged nucleus surrounded by two ... [a computational quantum-mechanical modelling method that looks at the electronic structure of many-body systems] would be a ...

One is Na₂He, which consists of one helium atom and two sodium atoms ... 15 to 1.1 million times Earth's atmospheric pressure. Its structure should be similar to that of Na₂He, but in place ...