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Inspired by the theoretical predictions, the fully hydrogenated form of germanene, also known as germanane, was synthesized in 2013 using topochemical deintercalation of the layered calcium digermanide (CaGe2 ). found that germanene appears to be in low-buckled form. The successful synthesis of silicene in 2012 boosted the surge to obtain germanene, a 2D form of germanium analogous to graphene, bolstered by another prediction in which Cahangirov et al. Introduction Graphene synthesis spurred the quest to obtain two-dimensional (2D) forms of other materials in group IV of the periodic table as predicted by Takeda and Shiraishi in 1994. There was no significant improvement found in the doped gas sensing capability of germanene over the vacancy defects, except for CO2 upon adsorption on N-doped germanene. Additionally, the influences of substituted dopant atoms such as B, N, and Al in the germanene nanosheet have also been considered to study the impact on its gas sensing ability. Projected density of states provides detailed insight of the gas molecule’s contribution in the gas-sensing system. The enhancement of the interactions between gas molecules and the germanene nanosheet has been further investigated by density of states. Mulliken population analysis imparts that an appreciable amount of charge transfer occurs between gas molecules and a germanene nanosheet which supports our results for adsorption energies of the systems. Our calculations have revealed that while a pristine germanene nanosheet adsorbs CO2 weakly, H2 S moderately, and SO2 strongly, the introduction of vacancy defects increases the sensitivity significantly which is promising for future gas-sensing applications. Calizo∗ Department of Electrical and Computer Engineering, Florida International University, Miami, FL, USAĪ r t i c l e Keywords: Toxic gas Sensor Vacancy defects Doping Germanene nanosheetĪ b s t r a c t First-principles calculations based on density functional theory (DFT) have been employed to investigate the structural, electronic, and gas-sensing properties of pure, defected, and doped germanene nanosheets. Surface Science journal homepage: Doping and defect-induced germanene: A superior media for sensing H2 S, SO2, and CO2 gas molecules M.M. For instance, if the electrons for a carbon atom given by the Mulliken charge population is 3.5, the charge transfer between this carbon atom and its nearest neighbors will be 0.5 e since an isolated carbon atom has 4 electrons, and its neighbors transfer 0.5 e to this carbon atom.Contents lists available at ScienceDirect And then calculate the eigenstate for such energy position (or molecule level).įor the third question, the Mulliken charge population can give the number of electrons for each atom. First, do the projected density of states (DOS) calculations and find out the energy regions (or energy position) for the states with only from the pi-orbital. But one can obtain the isosurface plot of an eigenstate that from pi-orbital.
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The quantum number for HOMO + 1 = The quantum number for LUMO.įor the second question, your description is not clear.
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Remind that the quantum number for the first molecule level is defined as zero, i.e., the index for the molecule levels in ATK starts from zero. Assuming the total electrons of a molecule is N, if N is odd, the quantum number for HOMO in ATK will be (N+1)/2 if N is even, the quantum number for HOMO in ATK will be N/2.
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A very simple rule of thumb is that the quantum number for HOMO can be counted by the Pauling principle: each level can be occupied with 2 electrons. Of course, the quantum numbers for the HOMO and LUMO of a molecule are different to those of other one.