Closed m-a-saleh closed 2 months ago
In Step 4, you need to specify a FC2XML file that containts harmonic force constants calculated using the same supercell size as the input structure (1x2x1 supercell, in your case).
So, please generate supercell1x2x1_0.03.xml
first using the finite displacement approach.
I want to use different supercell sizes for FC2 and FC3. For FC2 I want to use 2x4x1 supercell, while for FC3 I want to use 1x2x1 supercell.
I have followed these steps:
super2x4x1_0.03.xml
file.DFSET_randomQ
file.&optimize
block with FC2 fixed to the previously calculated values:The last step results in the following error:
How to make sure that the number of harmonic terms in the new computational condition is the same as that in the FC2XML file generated using larger supercell.