zinc surface optimizing energy

[tjgus6142]

hello.
I am trying to calculate the optimising energy of a zinc surface per crystal face.
So, after optimising the zinc bulk, I cut it into three crystal faces (002), (100) and (101) using materials studio.
The widths of the faces were then determined using VESTA.
The (002) face was determined to be 8x8 and the (100) and (101) faces were determined to be 6x6.
Then, selective dynamics was used to create six layers, with the bottom three fixed and the top three movable.
Afterwards, I checked the energy via vef.pl and got the following results
(002) / 8x8 : -403.797643 eV
(101) / 6x6 : -428.141914 eV
(100) / 6x6 : -437.170397 eV

However, only (002) has a larger area (8X8) than the other crystal faces, so in order to compare the energy of each crystal face at the same area, the area of (002) was re-made into 6X6 to find the energy. The result is as follows.
(002) / 6x6 : -225.987372 eV

The energy changes significantly by about 200 eV as the area changes, and I wonder if I calculated it correctly.
Because for the (101) and (100) crystal faces, the values are similar at about 400 eV for a 6X6 area, but only the (002) crystal face has a large difference of about 200 eV for a 6X6 area, so I wonder if the calculation of the energy optimising on the 6X6 area of the (002) crystal face is correct.

[alexey.tal]

Hi,

We don't develop VTST tools, so I cannot comment if vef.pl works correctly.
I would suggest that you have a look at our tutorials on surface calculations:
https://www.vasp.at/wiki/index.php/Ni_1 ... relaxation
https://www.vasp.at/wiki/index.php/Ni_1 ... dstructure