constrained cell optimisation

[hfruchtl]

Dear all,

I want to optimise a 2-dimensional network of molecules while keeping
the inter-layer distance fixed at a large value. Is it possible to
constrain one lattice vector and the cell angles connected to it? Or
is there a different way of achieving what I want?

This question seems to have been asked here in 2008, and the answer
was "no", but one shouldn't give up hope...

Thanks in advance,

  Herbert