Correction for dispersion and Coulombic interactions in molecular clusters with density functional derived methods
Research output: Contribution to journal › Research article › Contributed › peer-review
Contributors
Abstract
The density functional based tight binding (DFTB) is a semiempirical method derived from the density functional theory (DFT). It inherits therefore its problems in treating van der Waals clusters. A major error comes from dispersion forces, which are poorly described by commonly used DFT functionals, but which can be accounted for by an a posteriori treatment DFT-D. This correction is used for DFTB. The self-consistent charge (SCC) DFTB is built on Mulliken charges which are known to give a poor representation of Coulombic intermolecular potential. We propose to calculate this potential using the class IV/charge model 3 definition of atomic charges. The self-consistent calculation of these charges is introduced in the SCC procedure and corresponding nuclear forces are derived. Benzene dimer is then studied as a benchmark system with this corrected DFTB (c-DFTB-D) method, but also, for comparison, with the DFT-D. Both methods give similar results and are in agreement with references calculations (CCSD(T) and symmetry adapted perturbation theory) calculations. As a first application, pyrene dimer is studied with the c-DFTB-D and DFT-D methods. For coronene clusters, only the c-DFTB-D approach is used, which finds the sandwich configurations to be more stable than the T-shaped ones.
Details
Original language | English |
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Article number | 244304 |
Journal | Journal of Chemical Physics |
Volume | 130 |
Issue number | 24 |
Publication status | Published - 2009 |
Peer-reviewed | Yes |
External IDs
Scopus | 67650472796 |
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Keywords
Keywords
- DER-WAALS COMPLEXES, SMALL BENZENE CLUSTERS, POTENTIAL-ENERGY SURFACE, PARTIAL ATOMIC CHARGES, TIGHT-BINDING METHOD, SCC-DFTB METHOD, AB-INITIO, IV CHARGE MODEL, PI-PI INTERACTIONS, INTERMOLECULAR INTERACTIONS