Hello,

I performed a DMol3 geometry optimization in Materials Studio. My goal is to fix the lattice parameters b and c, and also fix all lattice angles (α, β, γ), while allowing only the a lattice parameter to change.

In the Geometry Optimization settings, I enabled More → Optimize cell, and then ran the calculation. However, in the optimized result, all cell parameters (a, b, c, and angles) were changed, even though I intended to constrain b, c, and the angles.

For comparison, I tested the same model using the Forcite module, and in that case, only the a parameter changed, as expected.

Could anyone advise how to set up DMol3 geometry optimization so that only the a lattice parameter is relaxed, while keeping b, c, and all angles fixed?
If there is a specific constraint setting, input option, or recommended workflow, I would greatly appreciate your guidance.

Thank you.