Density functional theory (DFT) is a widely used methodology for the computation of molecular and electronic structure. Density-functional tight-binding (DFTB) is an approximate version of DFT offering higher computational efficiency with generally comparable accuracy. For carbohydrates, we found that the performance of DFTB is on par to DFT in terms of molecular geometries of heavy atoms and conformational energies. However, DFTB is known to underestimate hydrogen bonding interactions. In the context of carbohydrates, we found that DFTB shortens hydrogen bonds and extends bond angles, effectively leading to a compensation for the underestimation of hydrogen bonding interaction energies. The origin of this compensation was found in the DFTB potential energy associated with hydroxyl rotations, resulting in an overestimation of hydrogen bonding interactions.

Theoretical investigations of simple carbohydrates by density-functional tight-binding: A comparative analysis to density functional theory

255th National Meeting (2018)

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