Hello Bharath..
Wht u have done is correct only..it's breaking the loop virtually and it's one of the way for stability analysis...
The easy way is connect the Vin- and Out put through iprobe (which can be found in analogLib)
and add stb analysis ( what ever frequency range u want.)
Vin+ is connected to a Ac Source with Ac magnitude =1 and DC voltage as VDD/2 i mean the common mode voltage.
u will get the loop gain,PM,GM,UGB.
Hope this could help You.
With Best Regards
ShaDy205