Author Topic: RELAX error "force constant matrix will be read from $forceapprox ..." ...  (Read 5489 times)

turbomaster

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Q: I have deleted the files energy, gradient and forceapprox in order to start a new geometry optimization on the same system using the old control file. DSCF and GRAD run properly, but RELAX crashes with the error
 force constant matrix will be read from $forceapprox
 $forceapprox : could not find file  !
 relax step ended abnormally
 STOP  HREAD : error reading $forceapprox !
Why?

A: Because of the entry $forceinit off in the old control file, RELAX expects to find the approximate force constants to help it update the geometry. Change this to $forceinit on (simply enter finit at the command line to change it), rerun RELAX and then restart the geometry optimization from a DSCF step.