Dilithium, Li2, is a strongly electrophilic, diatomic molecule comprising two lithium atoms covalently bonded together.

[citation needed] Being the third-lightest stable[citation needed] neutral homonuclear diatomic molecule (after dihydrogen and dihelium), dilithium is an extremely important model system for studying fundamentals of physics, chemistry, and electronic structure theory.

It is the most thoroughly characterized compound in terms of the accuracy and completeness of the empirical potential energy curves of its electronic states.

[clarification needed][9] The most reliable of these potential energy curves are of the Morse/Long-range variety (see entries in the table below).

[10] This lithium oscillator strength is related to the radiative lifetime of atomic lithium and is used as a benchmark for atomic clocks and measurements of fundamental constants.