The first principles density functional theory (DFT) is applied to study effects of molecular adsorption on optical losses of silver (111) surface. The ground states of the systems including water, methanol, and ethanol molecules adsorbed on Ag (111) surface were obtained by the total energy minimization method within the local density approximation (LDA). Optical functions were calculated within the Random Phase Approximation (RPA) approach. Contribution of the surface states to optical losses was studied by calculations of the dielectric function of bare Ag (111) surface. Substantial modifications of the real and imaginary parts of the dielectric functions spectra in the near infrared and visible spectral regions, caused by surface states and molecular adsorption, were obtained. The results are discussed in comparison with available experimental data.
MAD-SURF: a machine learning interatomic potential for molecular adsorption on coinage metal surfaces
Universidad Autónoma de Madrid（马德里自治大学）；Aalto University（阿尔托大学）；Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid（马德里自治大学凝聚态物理中心（IFIMAC））；Nano Life Science Institute (WPI-NanoLSI), Kanazawa University（金泽大学纳米生命科学研究院（WPI-NanoLSI））
We perform first-principles calculations of electronic and dielectric properties of bismuthene functionalized with small ligands using first-principle calculations. We show that all functionalized structures have topological insulating (TI) behavior with a sizeable gap by calculating the Z$_2$ topological invariant. Furthermore the adsorption of all groups induce a quasi-planar structure to the initially pristine bismuthene structure. Finally we show that the dielectric properties show a large anisotropy with two main in plane absorption peaks.
The adsorption kinetics of CO on PdAu bimetallic clusters, containing 140 $\pm$ 12 atoms and a composition varying between 0% and 55% of Pd atoms, is investigated by a pulsed molecular beam method (MBRS). The clusters are grown on a nanostructured ultrathin film of alumina on Ni3Al (111) playing the role of a template which gives a hexagonal array of bimetallic clusters having a sharp size distribution and a uniform composition. The surface concentration calculated, assuming segregation of gold to the surface, varies between 0 and 90% of Au atoms on the surface. From the adsorption-desorption …
Density functional theory $(DFT)$ studies show that doping of $3d TM$ atoms into $Mg_4^{0,+} (TMMg_3^{0,+})$ can alter the endothermic nature of molecular hydrogen adsorption on bare $Mg_4^{0,+}$. $H_2$ adsorption on $TMMg_3^{0,+}$ clusters depends on the $TM(3d)$ orbital contribution to the frontier molecular orbitals of the clusters. In $H_2TMMg_3^{0,+}$ complexes, $H_2$ is adsorbed through donation and back donation of electronic charges with $TMMg_3^{0,+}$ clusters. $H_2$ binding energy is the maximum for $NiMg_3$ (-0.76 eV) and $FeMg_3^+$ (-0.48 eV) among the neutral and cationic $TMMg_3$…
Surface adsorption is one of the fundamental processes in numerous fields, including catalysis, environment, energy and medicine. The development of an adsorption model which provides an effective prediction of binding energy in minutes has been a long term goal in surface and interface science. The solution has been elusive as identifying the intrinsic determinants of the adsorption energy for various compositions, structures and environments is non-trivial. We introduce a new and flexible model for predicting adsorption energies to metal substrates. The model is based on easily computed, int…
Magnetism Induced by Azanide and Ammonia Adsorption in Defective Molybdenum Disulfide and Diselenide: A First-Principles Study
State University of Campinas（坎皮纳斯州立大学）；Rice University（莱斯大学）；University of South Florida（南佛罗里达大学）；College of Technology, University of Brasília（巴西利亚大学技术学院）
The structure of the double-layer formed at the surface of carbon electrodes is governed by the interactions between the electrode and the electrolyte species. However, carbon is notoriously difficult to simulate accurately, even with well-established methods such as electronic Density Functional Theory and Molecular Dynamics. Here we focus on the important case of a lithium ion in contact with the surface of graphite, and we perform a series of reference Quantum Monte Carlo calculations that allow us to benchmark various electronic Density Functional Theory functionals. We then fit an accurat…
Molecular Adsorption of H2O on TiO2 and TiO2:Y Surfaces
S.U. Umarov Physical-Technical Institute of the National Academy of Science of Tajikistan（塔吉克斯坦国家科学院S.U.乌马尔物理技术研究所）；Osimi Tajik Technical University（塔吉克技术大学奥西米分校）；Joint Institute for Nuclear Research（苏联联合核子研究所）；Dubna State University（杜布纳国立大学）；Nanotechcenter LLC（纳米技术中心有限责任公司）；Lusófona University, IDEGI（卢索丰大学IDEGI）
Progress in structure recovery from low dose exposures: Mixed molecular adsorption, exploitation of symmetry and reconstruction from the minimum signal level
我们调查的恢复结构从大面积，低剂量的曝光，分布在许多相同的副本的一个对象的剂量。重建是通过极大似然方法完成的，该方法既不需要识别也不需要对齐单个粒子。我们还模拟了石墨烯上的小分子吸附物，并演示了从\add{large area and}极低剂量原始数据中检索原子分辨率的图像。如果利用支持膜的所有对称性（平移、旋转和镜像）来恢复单个吸附分子的结构，则低至5 $e^{-}/$/$^{2}$的剂量就足够了。我们比较了不同的优化方案，考虑了混合分子和吸附位点，以及对数据量的要求。我们进一步证明了极大似然方法只需要每个实体至少有三个独立的计数，最后，我们证明了该方法与真实的实验数据和畸变的存在。
Microporous organosilicas assembled from polysilsesquioxane (POSS) building blocks are promising materials that are yet to be explored in-depth. Here, we investigate the processing and molecular structure of bispropylurea bridged POSS (POSS-urea), synthesised through the acidic condensation of 1,3-bis(3-(triethoxysilyl)propyl)urea (BTPU). Experimentally, we show that POSS-urea has excellent functionality for molecular recognition toward acetonitrile with an adsorption level of 74 mmol/g, which compares favourably to MOFs and zeolites, with applications in volatile organic compounds (VOC). The …
Molecular adsorption at the surface of a 2D material poses numerous questions regarding the modification to the band structure and interfacial states, which of course deserve full attention. In line with this, first-principle density functional theory is employed on the graphene/ammonia system. We identify the effects on the band structure due to strain, charge transfer and presence of molecular orbitals (MOs) of NH3 for six adsorption configurations. The induced strain upon ammonia-adsorption opens the bandgap (Eg) of graphene due to the breaking of translational symmetry and shifts the equil…
We investigate the adsorption and diffusion behaviors of CO2, CH4, and N2 in interfacial systems composed of a polymer of intrinsic microporosity (PIM-1) and amorphous silica using grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations. We build model systems of mixed matrix membranes (MMMs) with PIM-1 chains sandwiched between silica surfaces. Gas adsorption analysis using GCMC simulations shows that gas molecules are preferentially adsorbed in microcavities distributed near silica surfaces, resulting in an increase in the solubility coefficients of CO2, CH4, and N2 compar…
Molecular reference corrections for quantum Monte Carlo adsorption energies
SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory（斯坦福直线加速器中心界面科学与催化中心）；Department of Chemical Engineering, Stanford University（斯坦福大学化学工程系）；SLAC National Accelerator Laboratory（斯坦福直线加速器中心）；Stanford University（斯坦福大学）
Organic adlayers on inorganic substrates often contain adatoms, which can be incorporated within the adsorbed molecular species, forming two-dimensional metal-organic frameworks at the substrate surface. The interplay between native adatoms and adsorbed molecules significantly changes various adlayer properties such as the adsorption geometry, the bond strength between the substrate and the adsorbed species, or the work function at the interface. Here we use dispersion-corrected density functional theory to gain insight into the energetics that drive the incorporation of native adatoms within …
The role of catalyst support and regioselectivity of molecular adsorption on a metal oxide surface is investigated for the NO reduction on a Cu/γ-alumina heterogeneous catalyst. For the solid surface, computational models of the γ-alumina surface are constructed based on the Step-by-Step Hydrogen Termination (SSHT) approach. Dangling bonds, which appear by cutting the crystal structure of a model, are terminated stepwise with H atoms until the model has an appropriate energy gap. The obtained SSHT models exhibit the realistic infrared (IR) and ultraviolet-visible (UV/Vis) spectra. Vibronic cou…
Nuclearity of Copper Clusters on hBN/SiC Heterostructure Modulates Molecular Adsorption
Aalto University（阿尔托大学）；European Laboratory for Learning and Intelligent Systems (ELLIS) Institute Finland（欧洲学习与智能系统实验室芬兰研究所）；University of Eastern Finland（芬兰东部大学）；HUN-REN Wigner Research Centre for Physics（匈牙利研究与教育网络维格纳物理研究中心）；Budapest University of Technology and Economics（布达佩斯技术与经济大学）；Loughborough University（拉夫堡大学）
The large number of possible structures of metal-organic frameworks (MOFs) and their limitless potential applications has motivated molecular modelers and researchers to develop methods and models to efficiently assess MOF performance. Some of the techniques include large-scale high-throughput molecular simulations and machine learning models. Despite those advances, the number of possible materials and the potential conditions that could be used still pose a formidable challenge for model development requiring large data sets. Therefore, there is a clear need for algorithms that can efficient…
pH-Responsive Glyphosate Adsorption on Hydroxylated Carbon Nanotubes: From Electronic Structure to Molecular Dynamics
Universidade Federal de Alfenas - UNIFAL-MG（阿尔芬纳斯联邦大学）；Instituto de Ciências Exatas - ICEx（理学院）；Laboratório de Modelagem Computacional - La Model（计算建模实验室）；Institute of Science and Tecnology - ICT（科学技术研究所）
We report the growth of epitaxial LaInO3 on DyScO3(110) substrates by adsorption-controlled plasma-assisted molecular beam epitaxy (PA-MBE). The adsorption-controlled growth was monitored using line-of-sight quadrupole mass spectrometry. In a thermodynamics of MBE (TOMBE) diagram, the experimental growth window was found to be significantly narrower than the predicted one. We found the critical thickness for strain relaxation of the LaInO3 layer (lattice mismatch $\approx$ -4$\%$) to be of 1 nm using in-situ RHEED analysis. Substrate and film possess an orthorhombic crystal structure which can…
Selective Adsorption of a Supramolecular Structure on Flat and Stepped Gold Surfaces
卤代芳香分子在表面上聚集形成氢键和卤键。尽管这些系统已经在平坦的金属表面上进行了深入的研究，但高指数邻位表面仍然具有挑战性，因为它们可能会诱导复杂的吸附物结构。用van der Waals修正的密度泛函理论研究了2，6-二溴蒽醌（2，6-DBAQ）在平坦和台阶状金表面上的吸附.系统地研究了各种不同吸附构型的平衡几何构型和相应的吸附能。结果表明，桥位和台阶边缘是单分子在平坦和台阶表面上的首选吸附位点。范德华相互作用，卤素键和氢键的作用进行了探索的单层覆盖的2，6-DBAQ分子，揭示了分子的灵活性和分子间的相互作用稳定的平面和阶梯表面上的二维网络。我们的结果提供了一个合理的实验观察过渡金属的高指数邻位表面上的分子地毯。
