Affiliate  Member, International Union of Pure and  Applied Chemistry.

Life Member, International Society for Theoretical Chemical Physics.

Life Member, Chemical Research Society of India.

Selected  for the International Exchange Programme  between  INSA and DFG (Germany).

Formerly  Research  Associate  :

1. University  of  North Carolina, Chapel Hill, USA,

2. Institut for Organische Chemie,Erlangen‑Nurnberg, Germany.

Formerly Visiting  Professor:

1. Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.

2. Departamento de Quimica Fisica, Facultad de Quimica, Pontificia Universidad Catolica de Chile, Santiago,Chile.

3. Departamento de Quimica,Universidad Autonoma Metropolitana-Izatapalapa, Mexico D.F.

4. Universidad Michoacana de San Nicolas de Hidalgo, Morelia, Mexico.  

Member, FWO, Belgium.

Task force leader : IIT-KGP Vision 2020 , Research excellence.

Senate Member IISER (Kolkata)

Expert, Review Committee, IIT Bombay.