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<div>Dear QE users:
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I want to do the 'vc-relax' calculation of bilayer structure of graphene and BN. And only the lattice constant a, b are allowed to change in the relaxation. So I set cell_dofree = 'xy' , but when the calculation finished, the distance of of the vacuum between different by layers also changed. The vacuum is set 10 A, it changed to 5.76 A in the end. What can be the reasons ? Any suggestions will be greatly appreciated.
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cell_dofree CHARACTER
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Default: 'all'
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Select which of the cell parameters should be moved:
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all = all axis and angles are moved
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x = only the x axis is moved
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y = only the y axis is moved
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z = only the z axis is moved
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xy = only the x and y axis are moved, angles are unchanged
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xz = only the x and z axis are moved, angles are unchanged
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yz = only the y and z axis are moved, angles are unchanged
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xyz = x, y and z axis are moved, angles are unchanged
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shape = all axis and angles, keeping the volume fixed
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Research Laboratory for Computational Materials Sciences, Institute of Solid State Physics,
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Chinese Academy of Sciences
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