[DFTB-Plus-User] How to set the pressure at a certain direction?

[Yecheng Shao]

Hello, 
I am trying to simulate some elastical behaviour like tensile, shearing, etc.
For example, when a 3d simulation box is stretched in x direction, tensile stress will appear at boundaries norm to y and z direction if the box is fixed. This structure can be optimized by using the Fixlengths command.
However, the pressure in Driver only support one dimension value, how can I optimized the structure when I try to stretch in one dimension while keeping the pressure on rest directions at specified nonzero value, eg., stretching 20% strain in x direction while keep the pressure on y as 100GPa and z as 200GPa.
Ps. How is the pressure of simulation box related to the stress tensor?

Thanks,
Yecheng Shao

Zhejiang University

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