Could you please rewrite the last sentence?
During the vc-relax procedure, the Fourier transform grid is kept fixed to avoid Pulay stress. The condition to incldue a certain plane wave in the basis set is hbar |G|^2 < Ecutwfc, and G is an integer linear combination of the reciprocal basis vectors b1, b2, b3. These b_i vectors change when the volume changes, which means that at the end of the relax, the basis set is not consistent with the cutoff and may be anisotropic. If you repeat the relax from scratch using the previous final configuration as the initial one, you may get different results. Rinse and repeat until you don't.
cheers -- Lorenzo Paulatto - Paris _______________________________________________ users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users
