Prof. Dr. Stefan Grimme

Method Development

• Developement of the DFT-D3 method and its precursors (now called DFT-D1 and DFT-D2). Although the 'dispersion-problem' in DFT was well-known since about 15 years and DFT-D-type methods had been proposed by others, it could be shown in 2004 for the first time that the approach solves the problem in a rather general way and that the correction can be coupled in a simple form to standard density functionals. The in 2010 proposed DFT-D3 method includes several new ideas to make it less empirical and more accurate and to extend it consistently to the whole periodic table. It is just now replacing DFT-D2 as the world-wide de-facto standard in dispersion corrected DFT calculations. The B97-D functional from 2006 was the first GGA that incorporates dispersion terms from the very beginning. DFT-D3 and B97-D have been implemented in all major codes. The two latest DFT-D versions are meanwhile also used routinely in periodic solid-state calculations. It opens completely new possibilities for the application of DFT in the areas of condensed matter, materials science or bio-chemistry where dispersion effects are often of utmost importance.
  Refs.[102,125,126,141,144,150,182,229,230,236,247,248,249,252]
• Evaluation and improvement of density-based dispersion corrections of non-local (NL) vdW-DF type. First applications of this method to typical thermochemical problems and applications with hybrid functionals are conducted (termed DFT-NL). Such methods can be used complementary to DFT-D3 in many applications. The Vydrov-vanVoorhis functional VV10 has been adapted to standard density functionals and implemented self-consistently into ORCA.
  Refs.[261, JCTC in press]
• Double-hybrid density functionals (DHDF) were proposed in 2006. DHDFs represent the fifth (highest) class of current density functionals and include non-local correlation effects and employ information about virtual Kohn-Sham orbitals. The first developed functional B2PLYP (2006) at that time was the most general and most accurate DFT method for general chemistry applications to molecules and has meanwhile been implemented in all major quantum chemistry codes. It can be considered as the 'true' successor of the popular B3LYP functional. Many B2PLYP clones have been proposed since then and this has stimulated a lot of research activity on non-local correlation functionals of related RPA type.
  Refs.[131,139,153,156,228,244]
• Together with F. Neese the TD-DHDF method was developed which extends DHDFs to the area of excited states. For example TD-B2PLYP is currently the most accurate DF method for low-lying excitations in main group systems. It provides unprecedented accuracy e.g. for large unsaturated chromophores for which standard TDDFT often yields qualitatively wrong results (e.g. state orderings).
  Refs.[164,188,197,206,264]
• The SCS-MP2 electronic structure method was proposed in 2003. It increases the accuracy of MP2 significantly at no additional computational overhead. It has become a standard tool in computational chemistry and is now implemented in all major program packages. The general spin-component scaling (SCS) idea opened a new field in quantum chemistry and meanwhile many follow-up methods have been reported by researchers world-wide (e.g. SCS-CCSD, SCS-CC2, SCS-CIS(D), S2-MP2, SCS(MI)-MP2, SOS-MP2).
  Refs.[86,92,93,100,101,105,106,113,119,133,155,216,233]
• Development of MP2.5 which is a scaled variant of third-order MP perturbation theory for the computation of accurate non-covalent interaction energies (together with the group of P. Hobza). Estimated MP2.5/CBS energies very closely approach the accuracy of the current gold-standard CCSD(T) but can be evaluated for much larger systems with about 100 atoms routinely.
  Refs.[196,214]
• Simplified multi-reference perturbation methods (MR-MPn) and a corresponding computer program using RI for large systems have been developed.
  Refs.[54,61,71,73]
• Its successor is the DFT/MRCI method (1999) which still represents one of the rare DFT methods for multi-reference (MR) cases. It is used by several research groups (e.g. Christel Marian at the University Düsseldorf) to routinely compute excited state properties of large molecules with DFT. The method partially solves the 'double-excitation' problem in TDDFT which is relevant for many important chromophores. The corresponding computer code represents the first implementation of the efficient RI-approximation for CI and MR-MP calculations.
  Refs.: [49,53,62,63,78,198]
• The DFT/SCI method was at the time of its development (1996) the only generally applicable DFT method to routinely compute electronic spectra (UV and CD) of molecules. It turned out to be similar to the later developed TDA-DFT method of M. Head-Gordon.
  Refs.: [22,28,30,31,32,35,38,43,48]
• Quantum chemical calculations of CD-spectra and optical rotations (OR) for the assignment of the absolute configuration of molecules were established in the 90s. Various methods (semi-empirical, CI, DFT) have been used. Work along the same lines was done later by P. J. Stephens (with more emphasis on OR). One of the first TDDFT calculations of OR also using RI techniques have been undertaken. The first electronic wave function based continuous symmetry measure (similar in application to D. Avnir's classical measure) has been developed in 1995 for the analysis of chiral systems.
  Refs.[7,14,15,20,30,32,36,39,55,64,67,70,74,83,145,187]
• A general intermolecular force-field based on monomer (semi-empirical) quantum chemical information (VDW3) has been developed. It is based on DFT-D3 and will be used in the future in a QM/MM context for the improved description of e. g. solvent effects. A first application for computing adsorption isotherms of small molecules in porous materials by by GCMC simulations demonstrates the accuracy of the method.
  Refs.[JPC C, submitted]
• Grid-Computing: QMC@HOME as implemented in Münster in 2007 was the first world-wide established grid (cloud) computing project in quantum chemistry with currently > 15000 participants. It was developed originally for electronic diffusion quantum Monte-Carlo (DMC) calculations but is meanwhile used more and more for large scale DFT calculations using the ORCA quantum-chemical program (e.g. for sampling the conformational space of large bio-organic molecules).
  Refs.[177,266,267]

Recent Applications and Computational Chemistry

• Non-covalent interactions in large molecules, complexes and condensed matter systems, stacking interactions. Analysis and non-additive contributions.
  Refs.[121,127,157,171,177,180,182,185,209,234,235,236]
• London dispersion effects for thermochemistry and intramolecular dispersion.
  Refs.[100,130,173,195,204,229,232,262]
• Thermochemical benchmarking (development of benchmark sets and calculation of accurate reference data).
  Refs.[119,202,203,223,232,243,244,245]
• DNA fragments, peptides and proteins.
  Refs.[144,177,185,182,183,266]
• Theoretical conformational analysis and assignment of absolute configuration of chiral molecules by theoretical OR and CD.
  Refs.[134,145,161,167,187,188,190,242,226]
• Theoretical description of so-called frustrated Lewis pairs (FLPs) and their reactions, which is currently one of the 'hottest' topics in synthetic chemistry (e.g. for H₂ or CO₂ activation).
  Refs.[170,211,213,224,227,241,246,257,258,259,260]
• Computional chemistry for organic transition metal complexes.
  Refs.[104,114,160,166,184,204,222,262]
• Analysis and interpretation of correlation effects in prototypical organic molecules (e.g. alkanes and aromatics) with special attention to DFT failures.
  Refs.[105,152,135,149,192,199]
• Excited electronic states and UV spectra.
  Ref.[103,105,107,120,148,164,175,206,233]

Current Research Projects and Perspectives

• Development of dispersion-corrected density functionals (DFT-D3) with improved performance and reduced self-interaction error which is a fundamental problem in DFT.
• Development of very accurate hybrid- and double-hybrid functionals with improved performance and broader range of application (using e.g. RPA).
• Development of simplified (semi-empirical) quantum-chemical methods for about 10000 atoms (bio-organic systems).
• Investigation of quantum-chemistry based drug-ligand 'scoring' functions.
• Application of dispersion-corrected DFT to surface (adsorption and reaction) and liquid phase problems (e.g., phase de-mixing in combination with Monte-Carlo techniques).
• Further development of extensive thermochemical benchmark sets and detailed assessment of electronic structure methods.
• Theoretical investigation of chemical activation of small molecules. The work on FLP chemistry will be continued in close collaboration with the G. Erker and D. Stephan groups. In this context we have developed an electric field model of activation which might help to discover entirely new reactions.
• Exploration of chemical reaction mechanisms and spectroscopic problems in close collaboration with experimentalists.
• Investigation of non-additive (cooperative) effects in non-covalent interactions. This work is strongly related to the SFB 858.
• Further exploration of the recently introduced new concept of 'dispersion energy donors', i.e., functional chemical groups that stabilize certain structure or bonding situations by dispersion interactions. This might eventually lead to additional design principles for e.g. (stereo-selective) catalysts.