Respected Erik Marklund, Thank you for your reply When i run with a -noappend option from the checkpoint it runs well but Ooutput files are in Different Names The files Are not merged (are not Continues) ./mdrun_d -s CNTPEPRSOLNPT.tpr -cpi CNTPEPRSOLNPT_prev.cpt -v -nt 8 -deffnm CNTPEPRSOLNPT -noappend