Előadó: BILL POIRIER (ELTE TTK Komplex Rendszerek Fizikája tanszék / Department of Chemistry and Biochemistry Texas Tech University, vendéglátó: Szalay Viktor)

Előadás címe: Exact Quantum Dynamical Treatment of Hydrogen-material Interactions

Időpont: 2017. február 14. (kedd) 10:00 (1 óra)
Helyszín: MTA Wigner FK SZFI, I. épület 1. emeleti Tanácsterem


Hydrogen, H2, is arguably the most well understood molecule. Yet remarkably, our mechanistic understanding of hydrogen-material interactions remains limited—despite much interest, e.g., in the contexts of hydrogen fuel storage, catalysis, etc. Simulations are challenging, owing to the need to treat quantum dynamical effects accurately. Conversely, nuclear magnetic resonance and inelastic neutron scattering experiments provide useful data, but are difficult to interpret properly without theory. This talk addresses the fundamental quantum dynamical interactions of hydrogen with three specific material substrates: (1) C60 fullerene; (2) (5,5) single-walled carbon nanotube; (3) Fe(II)-dihydride(dihydrogen) “Kubas” complex, Fe(H)2(H2)(PEtPh2)3 .

For the first system, an unexpected inelastic neutron scattering selection rule was recently discovered [1], contradicting previously held beliefs in the neutron community. We present a simple physical understanding of the new selection rule based on group theory, and also demonstrate that the set of forbidden transitions is much larger than previously reported.
For the second system, the migration of H atom adsorbates is analyzed, addressing ramifications for hydrogen storage via catalytic spillover [2]. Spin-polarized density functional theory (DFT) calculations are performed for a single adsorbate, and used to compute all bound rovibrational states—revealing a coherent quantum dynamical migration mechanism. A subsequent DFT and quantum dynamical study performed under the more realistic conditions of full H-atom coverage explains why the overall energetics are so favorable to spillover.
Finally, a DFT and quantum dynamical investigation of the Fe(H)2(H2)(PEtPh2)3 complex is conducted - specifically, of the full rotational motion of the dihydrogen ligand [3]. Rotation is the most important dynamical player at low temperature, and is also expected to play an important role in the fluxional reorganization of the ligands via quantum tunneling.

[1] M. Xu et al., J. Chem. Phys. 139, 064309 (2013); B. Poirier, J. Chem. Phys. Communication 143, 101104 (2015).
[2] J. L. McAfee and B. Poirier, J. Chem. Phys. 130, 064701 (2009); J. L. McAfee and B. Poirier, J. Chem. Phys. 134, 074308 (2011).
[3] N. Doslic, et al., Inorg. Chem. 50, 10740 (2011); M. Gonzalez, J. Eckert, A. Aquino, and B. Poirier, J. Chem. Phys. (in preparation).

Részletes információ: http://www.szfki.hu/seminar