preparation for verifying large blocks

Hi expert,

I will go to verification(dc) for upper hierarchy soon.

What should I be careful about convergence?

 a) node set 

 b) dcOp: use the prepared file, it was solved Op with lower gmin.

 c) mitigation of iabstol, vabstol: this is not good for tolerance

 d) increasing behavior model

Please tell me your ideas. 

Thanks,

Ichiro