Adding vacuum in monolayer structure

[anibose3]

Dear Sir,
Is there anyone who can tell that how can I add 20A vacuum layer in monolayer WSe2 structure using Quantumwise.Where I can get this option?

[Petr Khomyakov]

In the Builder, you should select Bulk Tools -> Lattice Parameters, and then increase the lattice parameter of the WSe2 unit cell in the out-of-plane direction to enlarge the vacuum thickness in between neighboring monolayers of WSe2. 

[Manish95]

In the Builder, you should select Bulk Tools -> Lattice Parameters, and then increase the lattice parameter of the WSe2 unit cell in the out-of-plane direction to enlarge the vacuum thickness in between neighboring monolayers of WSe2.

How much should be the length of this vacuum?

[Petr Khomyakov]

It should be chosen large enough to avoid spurious interactions between periodic images.  You should try to increase until you see no effect (within some tolerance indeed) on the quantities of your interest.