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SUMMARY:New 'low-cost' electronic structure methods for large systems - Pr
 of. Stefan Grimme\,  University of Bonn
DTSTART:20231016T130000Z
DTEND:20231016T133000Z
UID:TALK207148@talks.cam.ac.uk
CONTACT:Dr Philipp Pracht
DESCRIPTION:All widely used semi-empirical quantum chemical methods like P
 M6\, DFTB\, or GFN-xTB are formulated in a (almost) minimal basis set of a
 tomic orbitals\, which limits the achievable accuracy for many important c
 hemical properties. Recently\, we proposed a new special purpose tight-bin
 ding (TB) electronic Hamiltonian termed PTB[1] which is expressed in an ac
 curate polarized valence double-zeta AO basis set (vDZP). The basis has be
 en specially optimized in molecular DFT calculations using standard ECPs f
 or all elements up to radon[2]. The PTB method aims primarily at reproduci
 ng the one-particle density matrix of a DFT reference calculation with the
  accurate wB97X-V[3] range-separated hybrid (RSH) density functional in ex
 actly the same AO basis. The combination of wB97X(-V) with vDZP/ECP and an
  adjusted D4 dispersion correction defines a new member in our hierarchy o
 f efficient composite electronic structure methods\, termed wB97X-3c[2]. T
 he basis set optimization concept is furthermore applied to a minimal set 
 of AOs which - as a totally new ingredient - is made adaptive\, i.e.\, rad
 ially different for symmetry distinct atoms in a molecule. This q-vSZP set
 [4] forms the basis of our third-generation tight-binding model GP3-xTB wh
 ich includes non-local Fock-exchange as well as other new many-center Hami
 ltonian terms (e.g.\, atomic correction potentials\, ACP). It aims at gene
 ral purpose (GP) applicability in chemistry and more closely approaches DF
 T accuracy than previous semi-empirical methods at only slightly increased
  computational cost. When the number of primitive Gaussians in q-vSZP is s
 omewhat reduced\, and this basis is coupled with wB97M-D4[5] and ACPs\, an
  extremely efficient new 3c-composite method dubbed wB97M-3c is obtained.\
 n\n# S. Grimme\, M. Müller\, A. Hansen\, J. Chem. Phys.\, 158 (2023)\, 12
 4111\n# M. Müller\, A. Hansen\, S. Grimme\, J. Chem. Phys. 158 (2023)\, 0
 14103\n# N. Mardirossian and M. Head-Gordon\, Phys. Chem. Chem. Phys. 16 (
 2016)\, 9904 \n# M. Müller\, A. Hansen\, S. Grimme\, J. Chem. Phys.\, in 
 press.               \n# N. Mardirossian and M. Head-Gordon\, J. Chem. Phy
 s. 144 (2016)\, 214110
LOCATION:Zoom link: https://zoom.us/j/92447982065?pwd=RkhaYkM5VTZPZ3pYSHpt
 UXlRSkppQT09
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