you should make a hypothesis, the TS can connect the reactants to the products. which kind of software you used? for example, in gaussian, you can use IRC to testify your TS.

Hi Kumar,

if I understand You right, You are searching for a computational method to decide weather a transition state You have created is a "concerted" one??? I suppose by "concerted" You mean in the sence of  concerted reaction, e.g.  multiple bond formations are happening in the same instance as opposed to this a reaction where multiple bonds are succesively formed.

By definiton a transition state is a first oder saddle point on the potential enery surface of your system. Hence correspondig to just one arrangement of atoms in your system. For a concerted reaction you need to create (find) this TS. For a not conceted reaction, there are multiple transition states for each succesive step one.  And You need to find all of them.

So to answer the first part. A transition state is concerted if You "build" it as a concerted one. As Wenacho Ji said, You might get help on finding the TS using IRC with the gaussion software package for example. However, always check whether Your TS is a real one: A transition state, defined as a first order saddle point on the PES, is a maximum along one direction and a minimum along all other directions and therefore is char- acterized by only one negative eigenvalue in the "Hessian Matrix". To identify a true transition statze the absence of more than one negative frequency has to be checked (-> Normal mode analysis!). 

If you want to find out wherter a reaction  is more likely to be a concerted one than stepwise it get even more complicated, computationally. You have to:

Good Luck! Maybe it is easier to think of a nice experiment to dicide whether the reaction you study is concerted or not.

First check whether the ts you got is a true TS or not by freq calculation, and then give a IRC run over it 

Thank you all for valuable suggestions...i got it now....