Tuning Hydrogenated Silicon, Germanium, and SiGe Nanocluster Properties Using Theoretical Calculations and a Machine Learning Approach

Abstract

There are limited studies available that predict the properties of hydrogenated silicon–germanium (SiGe) clusters. For this purpose, we conducted a computational study of 46 hydrogenated SiGe clusters (Si x Ge y H z , 1 < X + Y ≤ 6) to predict the structural, thermochemical, and electronic properties. The optimized geometries of the Si x Ge y H z clusters were investigated using quantum chemical calculations and statistical thermodynamics. The clusters contained 6 to 9 fused Si–Si, Ge–Ge, or Si–Ge bonds, i.e., bonds participating in more than one 3- to 4-membered rings, and different degrees of hydrogenation, i.e., the ratio of hydrogen to Si/Ge atoms varied depending on cluster size and degree of multifunctionality. Our studies have established trends in standard enthalpy of formation, standard entropy, and constant pressure heat capacity as a function of cluster composition and structure. A novel bond additivity correction model for SiGe chemistry was regressed from experimental data on seven acyclic Si/Ge/SiGe species to improve the accuracy of the standard enthalpy of formation predictions. Electronic properties were investigated by analysis of the HOMO–LUMO energy gap to study the effect of elemental composition on the electronic stability of Si x Ge y H z clusters. These properties will be discussed in the context of tailored nanomaterials design and generalized using a machine learning approach.

Deamidation reaction network mapping of pharmacologic and related proteins: impact of solvation dielectric on the degradation energetics of asparagine dipeptides

“…The single-event parameters of the Arrhenius relationship, logIJA) and E A were obtained by fitting lnIJk) versus T −1 over the temperature range 298-1500 K. This procedure was performed automatically using a modified version of the CalcK script previously employed by our group for reaction kinetics analysis. [29][30][31][32][33][34][35][36][37][38][39][40] Through linear regression analysis, we determined Arrhenius behavior was obeyed well for all reactions. The solvation impact of liquid phase kinetics is beyond the scope of this work but will be addressed in future studies following the work of Jalan et al, which computes liquid-phase kinetics in relation to both the solute and the solvent.…”

Data‐Driven Investigation of Monosilane and Ammonia Co‐Pyrolysis to Silicon‐Nitride‐Based Ceramic Nanomaterials

“…With an average absolute deviation of 18.1 kJ mol −1 from experimental measurements, the G3//B3LYP composite method was the most accurate for the standard enthalpy of formation prediction of ammonia, disilane, trisilane, and the silicon‐nitride diatomic molecule. Among experimental and calculated values for standard enthalpy of formation, the greatest deviations were seen for the nitrogen‐containing species ammonia and silicon‐nitride diatomic molecule; however, there is insufficient experimental data available to regress bond additivity corrections as we had done in our previous works [31,32] . The G3//B3LYP method was more accurate for calculating standard enthalpy of formation values than the B3LYP functional alone for ammonia and silicon‐nitride diatomic molecule which can be ascribed to the higher‐level corrections incorporated in the composite method.…”

“…Extensive details regarding the computational methodology for calculation of optimized electronic structures and statistical thermodynamics, including corrections for vibrational anharmonicity, have been discussed elsewhere [31,32] and are provided in the Supporting Information for convenience. The quantum chemical values have been used in our data-driven approach to assess cluster reactivity which is presented here.…”

“…As we mentioned in our previous study, the cyclic rhombus cluster (SN0) of 4 silicon atoms with a marginally puckered nature, has a SiÀ Si bond length of 2.371 Å and a SiÀ H bond length of 1.492 Å with the angles of the SiÀ SiÀ Si bonds at 87.7 and 92.3 degrees. [31] For the SN1 species, the SiÀ N and SiÀ Si bond lengths are 1.760 Å and 2.360 Å, respectively. The SiÀ NÀ Si, NÀ SiÀ Si, SiÀ SiÀ Si bond angles are 109.9, 87.5 and 75.2 degrees, respectively.…”

“…Among experimental and calculated values for standard enthalpy of formation, the greatest deviations were seen for the nitrogencontaining species ammonia and silicon-nitride diatomic molecule; however, there is insufficient experimental data available to regress bond additivity corrections as we had done in our previous works. [31,32] The G3//B3LYP method was more accurate for calculating standard enthalpy of formation values than the B3LYP functional alone for ammonia and silicon-nitride diatomic molecule which can be ascribed to the higher-level corrections incorporated in the composite method. Electron correlation effects due to the semiconducting or non-local nature of electrons from Si atoms and the lone pair electrons from N atoms in the clusters require demanding composite methods to predict accurate trends in thermochemical proper- ties, such as standard enthalpy of formation as function of varying Si and N composition.…”