Hi Priya...., I think you can read these paper how to calculate the surface and interface energy (: http://www.researchgate.net/publication/256746363  and PHYSICAL REVIEW B 1998, VOLUME 57, NUMBER 12, pp.7281 - 7291)....good luck.

Article Simulating vapour growth morphology of crystalline urea usin...

Use an accurate energy model, such as force fields with multipoles in the DMACRYS program. You cannot use simple force fields, that will never give quantitatively accurate results. Then "cut" slices of the crystal corresponding to different miller indices and prepare crystals consisting of 2D slabs separated by at least 15 Å of vacuum. The difference in lattice energy between the 2D slabs and the solid 3D structure is the surface energy. Please see papers by Graeme Day and Sally Price.

Dear Priya,

                                 to calculate the attachment energy of the different (hkl) faces of a given crystal, the best way is to use the Hartman-Perdok method. First you can determine the "character" of the face (flat, stepped, kinked) and then you can calculate the best profile (for each face).  Finally, you can calculate the attachment energy for each surface profile. 

The fundamental of the method can be found in

1) "Morphology and growth unit of crystals" Editor, I. Sunagawa, Terra Scientific, Tokyo (1989)

2) "Crystal Growth: An Introduction" Ed. P. Hartman, North Holland Series in Crystal Growth, Amsterdam 1973.

I' m sending you some papers published by my Research Group in order to give you some ideas about this kind of work.

Thanks for your attention and... all the best !

Dino