[CPMD-list] Molecular crystals !!

[Belabbas Imad]

Dear CPMD users,

I am currently trying to calculate the lattice parameters  of a monoclinic molecular crystal : Acetonitrile (C2NH3). For that I am relaxing the system for several values of the lattice parameters (the classical procedure !!). 

* Is it possible to relax the directly lattice parameters within CPMD ? (doing variable cell relaxation)

During my relaxations, I have encountered to following message:

ODIIS I Insufficient progress for K= 2; reset !

and one single geometry relaxation requires about 30 SCF cycles !!

* Is there a way to improve this ?

I have tried to use CG for the WFN relaxation instead of ODIIS but it seems that the method has not been implemented yet for periodic systems . (I had  the following message: PROGRAM STOPS IN SUBROUTINE k_pcgrad| Line Search not implemented yet )

* is the value of 5x1e-04 for the geometry convergence is reasonable !!!??

I am attaching the input file that I am using !!

Best regards,

Imad



             
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