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Electronegativity of atoms
May/17 paper in Nature Comm. »more info

Transfer of chirality
Feb/17 Paper published in Nature Chemistry including News&Views. »more info

Towards chemical recognition of molecules
Aug/16 Paper published in ACS Nano. »more info

Odehnal award
June/16 O. Stetsovych received Odehnal award »more info

Praemium Academiae
June/16 P. Jelinek received CAS award »more info

Imaging electrostatic field
May/16 paper in Nature Comm. »more info

O. Wichterle prize
May/16 P. Hapala received O. Wichterle prize for outstanding young scientists at the AS CR. »more info

On-surface chemical synthesis
Apr/16 paper in JACS »more info

Structural and Electronic Properties of Nitrogen-Doped Graphene
Mar/16 Paper in Phys. Rev. Lett. »more info

Role of the electrostatic force in AFM images
Mar/16 Paper in Phys. Rev. Lett »more info

Charge transport between two molecules
Sep/15 Paper in Phys. Rev. Lett »more info

The best poster ECOSS-31
Sep/15 Our work has been selected as the best poster in the ECOSS-31 conference. »more info

Paper in ACS Nano
Aug/15 Novel way of B,N-co doping of graphene demonstrated. »more info

paper in PRL and Physics
Aug/15 Our work has been published in Phys. Rev. Lett highlighted as Synopsis in Physics. »more info

Paper in Nature Comm.
Jul/15 High-resolution AFM images reported at room temperature. »more info

Paper in Nano Letters
Jun/15 The current and the force used for controlled atomic switching of silicon tetramer. »more info

O. Wichterle prize
May/15 M. Ondracek received O. Wichterle prize for outstanding young scientists at the AS CR. »more info

Is the Concept of Electronic Band Structure valid for Si Nanocrystals of few nm in Size?

There has been a long-standing discussion on whether or not an electronic band structure concept. i. e. energy-to-wavevector dispersion, can be assigned to zero-dimensional objects such as quantum dots (nanocrystals). To answer this question, we introduce a general method, which allows reconstruction of electronic band structure of nanocrystals from ordinary real-space electronic structure calculations. We carried out an extensive analysis of band structure of a realistic Si nanocrystals of up to 3 nm in size including full geometric and electronic relaxation with different surface passivating groups including hydrogen, hydroxyl and methyl groups. In particular, we combine this method with large scale Density Functional Theory calculations incorporating more than thousand of atoms to obtain insight into the luminescence properties of silicon nanocrystals, in dependence on their surface passivation and mechanical deformation. To demonstrate character of the band structure of Si nanocrystals, we calculate band dispersion along the &-X direction to compare it with a bulk counterpart. Based on this comparison, we conclude that the band structure concept is applicable to silicon nanocrystals with diameter larger than ~2 nm with certain limitations. In addition we will discuss impact of polarized surface hydroxyl groups or geometric distortion on momentum space selection rules important for light emission.

P. Hapala, K. Kůsová, I. Pelant, P. Jelínek Theoretical analysis of electronic band structure of 2- to 3-nm Si nanocrystals Phys. Rev. B 87 (2013) 195420(1) - 195420(13).