The influence of the DFT approach on the structure and relative stability of models for cellulose I allomorphs

Abstract

Different Kohn–Sham approaches have been considered to test their behavior in the description of some known properties of $\hbox {I}_\alpha$ and $\hbox {I}_{\beta }$ crystalline forms of native cellulose. Periodic calculations employing pristine and hybrid DFT functionals (PBE, B3LYP, PBE0 and M06-2X) together with three different atomic basis sets have been taken into account. Weak interactions have been estimated according to both London-like corrections and a specially designed meta-GGA functional. While approaches accounting for weak van der Waals forces are mandatory to reasonably predict lattice parameters, it arises that they do not improve too much the description of H-bonds. Actually, the corresponding bond lengths appear systematically underestimated by calculations. From the computational strategies here considered, PBE0-D is the one that better reproduce the particular structural properties of both allomorphs.