Recently, we introduced a concept of combinatorial chemistry to computational chemistry and proposed a new method called “combinatorial computational chemistry”, which enables us to perform a theoretical high-throughput screening of catalysts. In the present paper, we reviewed our recent application of our combinatorial computational chemistry approach to the design of new catalysts for high-quality transportation fuels. By using our combinatorial computational chemistry techniques, we succeeded to predict new catalysts for methanol synthesis and Fischer–Tropsch synthesis. Moreover, we have succeeded in the development of chemical reaction dynamics simulator based on our original tight-binding quantum chemical molecular dynamics method. This program realizes more than 5000 times acceleration compared to the regular first-principles molecular dynamics method. Electronic- and atomic-level information on the catalytic reaction dynamics at reaction temperatures significantly contributes the catalyst design and development. Hence, we also summarized our recent applications of the above quantum chemical molecular dynamics method to the clarification of the methanol synthesis dynamics in this review. 相似文献
The physical sorption of a series of cyclophosphamide drug derivatives with formula where x = 2, X = F (2), Cl (3), Br (4); x = 3, X = F (5), Cl (6), Br (7) and x = 4, X = F (8), Cl (9), Br (10) on the surface of fullerene C60 was studied using density functional theory (DFT) at B3LYP and B3PW91 levels. The most negative binding energies obtained using the B3LYP approach and corrected for geometrical BSSE and dispersion energies (gCP-D3-ΔEbinding) were measured for compounds 8 (among isolated drugs) and 13 (among complexes). The dipole moments of isolated drugs were obtained close to those of their complexes with C60 (∼4.0–5.5 Debye) indicating their hydrophililic nature that is an appropriate property appealing for drug delivery in biological media. The adsorption of all drugs on the surface of fullerene was endergonic with all of the ΔGadsorption > 0. The ΔHadsorption values at B3PW91 level were only negative for complexes 14–16 indicating their exothermic adsorption nature. The HOMO–LUMO band gaps of complexes 11–19 were about 2.7 eV and are comparable with the gap in C60 but are much smaller than the gaps in isolated drugs 2–10 (6.5–8.0 eV) reflecting the increase in electrical conductivities upon complexation. The QTAIM data supported the covalent character of the C–O, C–N and N–H bonds, the intermediate character of PO, P–O and P–N bonds while the electrostatic nature of PO…C(fullerene) interactions. According to the gCP-D3-ΔEbinding binding energies and ΔHadsorption values at B3LYP level, it seems that the complexes 12 and 13 can be the most promising prodrug + carrier delivery systems.
Sensitivity analysis (SA) is a commonly used approach for identifying important parameters that dominate model behaviors. We use a newly developed software package, a Problem Solving environment for Uncertainty Analysis and Design Exploration (PSUADE), to evaluate the effectiveness and efficiency of ten widely used SA methods, including seven qualitative and three quantitative ones. All SA methods are tested using a variety of sampling techniques to screen out the most sensitive (i.e., important) parameters from the insensitive ones. The Sacramento Soil Moisture Accounting (SAC-SMA) model, which has thirteen tunable parameters, is used for illustration. The South Branch Potomac River basin near Springfield, West Virginia in the U.S. is chosen as the study area. The key findings from this study are: (1) For qualitative SA methods, Correlation Analysis (CA), Regression Analysis (RA), and Gaussian Process (GP) screening methods are shown to be not effective in this example. Morris One-At-a-Time (MOAT) screening is the most efficient, needing only 280 samples to identify the most important parameters, but it is the least robust method. Multivariate Adaptive Regression Splines (MARS), Delta Test (DT) and Sum-Of-Trees (SOT) screening methods need about 400–600 samples for the same purpose. Monte Carlo (MC), Orthogonal Array (OA) and Orthogonal Array based Latin Hypercube (OALH) are appropriate sampling techniques for them; (2) For quantitative SA methods, at least 2777 samples are needed for Fourier Amplitude Sensitivity Test (FAST) to identity parameter main effect. McKay method needs about 360 samples to evaluate the main effect, more than 1000 samples to assess the two-way interaction effect. OALH and LPτ (LPTAU) sampling techniques are more appropriate for McKay method. For the Sobol' method, the minimum samples needed are 1050 to compute the first-order and total sensitivity indices correctly. These comparisons show that qualitative SA methods are more efficient but less accurate and robust than quantitative ones. 相似文献
