Is it possible to customize convergence criterion?

Dear all,

My model has convergence problem. But the result looks good. I wonder if it's possible to customize convergence criterion, so that I can know if a global parameter converges or not.

Thanks!
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Pu, ZHANG ??
Departamento de Física Teórica de la Materia Condensada,
Universidad Autónoma de Madrid,
Madrid, Spain.