Randić’s molecular connectivity index
Encyclopedia
The Randić index, also known as the connectivity index, of a graph
is the sum of bond contributions
where 
and 
are
the degrees of the vertices making bond i ~ j.
in 1975. It is often used in chemoinformatics for investigations of organic compound
s.
Graph (mathematics)
In mathematics, a graph is an abstract representation of a set of objects where some pairs of the objects are connected by links. The interconnected objects are represented by mathematical abstractions called vertices, and the links that connect some pairs of vertices are called edges...
is the sum of bond contributions
where and arethe degrees of the vertices making bond i ~ j.
History
This graph invariant was introduced by Milan RandićMilan Randić
Milan Randić is a Croatian American scientist who is one of the leading experts in the field of computational chemistry.-Birth and education:...
in 1975. It is often used in chemoinformatics for investigations of organic compound
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...
s.