Since the Schrödinger equation cannot be solved exactly for multi-electron systems, Chandra introduces two vital tools:

It provides step-by-step derivations without assuming the reader is a math prodigy.

Students seek the PDF version for several reasons:

For Indian students especially, Chandra’s book has been a staple for competitive exams like the CSIR-NET, GATE, and JAM. However, its popularity has spread globally due to its exceptional clarity.

A K Chandra. Tata McGraw-Hill, 1994 - Quantum chemistry - 390 pages. Google Books