Dear Elham For adsorption process, you should follow steps: 1- vc-relax your experimental primitive or conventional cell.
2-cleave your surface by miller indexes, and construct your slab. you must provide 15-20 A vacuum in z-direction. 3- only relax the slab with constrain in z and angles (alpha, beta, gamma). if you vc-relax the slab, then your z-direction lattice constant will change. if you model surface, then you must fix position of some 3-5 first layers as a bulk. if you model thin film, then you can relax all atoms, even low layers. 4- take frequencies to be sure that your slab is in local minimum. 5- add you adsorbant on the surface, and repeat steps 3 and 4. for DOS and BAND you need exact scf and high-k point, respectively. Regards David Foster Ph.D. Student of Chemistry -------------------------------------------- On Mon, 8/3/15, Elham <[email protected]> wrote: Subject: Re: [Pw_forum] vc-relax calculation To: [email protected] Date: Monday, August 3, 2015, 5:45 AM Dear David Thank you very much for answer my question. First I vc-relax the pure surface (obtain a b c) and then different molecules adsorb on surface do vc-relax (a b c) a slightly changed. for comparison result It is problem? Best RegardsElhamPh.D. Student of Chemistry -----Inline Attachment Follows----- _______________________________________________ Pw_forum mailing list [email protected] http://pwscf.org/mailman/listinfo/pw_forum _______________________________________________ Pw_forum mailing list [email protected] http://pwscf.org/mailman/listinfo/pw_forum
