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SUMMARY:Leveraging different steps of the electronic structure ladder to u
 nderstand H2 adsorption - Dr Yasmine Al-Hamdani\, University of Naples Fed
 erico II
DTSTART:20250616T130000Z
DTEND:20250616T133000Z
UID:TALK233488@talks.cam.ac.uk
CONTACT:Dr Fabian Berger
DESCRIPTION:Molecular adsorption is a fundamental factor in gas storage ap
 plications and boosting the adsorption of molecular hydrogen would greatly
  improve hydrogen technology. However\, adsorption interactions can be cha
 llenging to predict accurately. While density functional methods are routi
 nely used to model adsorption\, it is known that the choice of density fun
 ctional approximation (DFA) can have a considerable impact on the predicte
 d adsorption energies and mechanisms. Fixed-node diffusion Monte Carlo (FN
 -DMC) is a many-body wavefunction based method that provides highly accura
 te predictions in non-covalently bound systems\, where the uncontrolled er
 ror from the fixed-node approximation is typically small. As such FN-DMC c
 an be used to guide the use of DFAs and provide useful mechanistic insight
 s. However\, it has been previously shown that hydrogen adsorption can hav
 e a small degree of covalency on metal doped carbon allotropes. To gauge t
 he impact of the fixed-nodes in FN-DMC for weakly covalent interactions\, 
 we predict small analogous molecular complexes using coupled cluster theor
 y for reference. We find that coupled cluster theory and FN-DMC predict a 
 consistent picture of molecular hydrogen adsorption\, despite the fixed-no
 de approximation. Thus\, we build our understanding from the small molecul
 ar complexes to the large extended materials\, even as we tentatively go b
 eyond non-covalent interactions\, towards charge transfer and weak covalen
 t bonding. Ultimately\, we find that boosting the hydrogen molecule adsorp
 tion energy is not as straightforward as predictions from DFAs indicate.
LOCATION:https://zoom.us/j/92447982065?pwd=RkhaYkM5VTZPZ3pYSHptUXlRSkppQT0
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