Effect of the direct correlation function on phase diagram of the two-mode phase field crystal model

Abstract

Effects of the width of direct correlation function peak and the peak at k=0 on the phase diagram for the two-mode phase field crystal model are examined carefully. The results indicate that increasing the width of direct correlation function peak will expand the stability region of the ordered phases; however, increasing the ratio of peak width will significantly increase the fcc phase region but reduce the bcc phase region. Adding a negative Gaussian peak at k=0 to the two-mode approximate direct correlation function will compress the phase diagram and make the two-phase coexisting region narrow.