We present PyCDFT, a Python package to compute diabatic states using constrained density functional theory (CDFT). PyCDFT provides an object-oriented, customizable implementation of CDFT, and allows for both single-point self-consistent-field calculations and geometry optimizations. PyCDFT is designed to interface with existing density functional theory (DFT) codes to perform CDFT calculations where constraint potentials are added to the Kohn–Sham Hamiltonian. Here, we demonstrate the use of PyCDFT by performing calculations with a massively parallel first-principles molecular dynamics code, Qbox, and we benchmark its accuracy by computing the electronic coupling between diabatic states for a set of organic molecules. We show that PyCDFT yields results in agreement with existing implementations and is a robust and flexible package for performing CDFT calculations. The program is available at https://dx.doi.org/10.5281/zenodo.3821097 . 相似文献
Highly crosslinked organic–inorganic hybrid polymer poly(cyclotriphosphazene-co-melamine) microspheres (PZM) were synthesized by a simple method. The microspheres was characterized by FTIR, SEM and EDX. It was applied to eliminate thorium(IV) from aqueous solution under various conditions, i.e., pH, initial concentration, dosage and contact time. The experimental data were well-imitated via the pseudo-second-order kinetic model and its adsorption processes comply with the Langmuir isotherm model. Adsorption thermodynamic studies demonstrated that the adsorption process, in essence, was spontaneous and endothermic. Furthermore, the maximum experimental adsorption capacity was 98.6 mg g?1 for initial thorium(IV) concentration 50 mg L?1. When pH?=?0.0, the thorium(IV) removal efficiency reached at 76.9%, which indicates that the adsorbent can also was used in a peracid environment. Adsorption behavior of thorium(IV) onto the microspheres were weakly affected via temperature, implying that adsorption would be done at room temperature.
BiOBr synthesized by alcoholysis precipitation is used in the preparation of BiPO4/BiOBr composites by adding H3PO4. Pristine BiOBr and a series of BiPO4/BiOBr composites have been successfully synthesized using an entirely room-temperature production process. X-ray powder diffraction, scanning electron microscopy, High-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, UV–vis absorption spectroscopy were used to investigated the bulk structure, surface morphology, element composition and optical properties of the samples. The degradation effect of different proportions of BiPO4/BiOBr composites, BiOBr and BiPO4 on Rhodamine B (RhB) was evaluated under visible LED light irradiation. Compared to pure BiOBr and BiPO4, the as-synthesized BiPO4/BiOBr composites showed enhanced performance, with 30% BiPO4/BiOBr composite showing the best performance, as it could degrade 95.66% of RhB (100 ml, 15 mg/L) within 120 min. The enhanced photocatalytic activity of BiPO4/BiOBr was attributed to the heterojunction formation between BiOBr and BiPO4 and efficient charge separation. 相似文献
Two dinuclear LnIII-based clusters, namely [Dy2L2(NO3)2(DME)4] ( 1 ) and [Gd2L2(NO3)2(DME)4] ( 2 ) [H2L = (E)-2-((2-hydroxybenzylidene)amino)phenol] were obtained under hydrothermal condition. Two LnIII ions are bridged by two phenolic hydroxyl oxygen atoms, and the distances of them are 3.829 Å (Dy1–Dy1A) and 3.860 Å (Gd1–Gd1A). Two Dy1–O–Dy1A and Gd1–O–Gd1A angles are 109.4° and 109.8°, respectively. Magnetic studies reveal a weak antiferromagnetic interaction between Gd ions in complex 2 , and single-molecule magnet behavior for 1 with Ueff = 49.9 K and τ0 = 1.54 × 10–6 s. 相似文献
Herein we report an efficient synthesis to prepare O-doped nanographenes derived from the π-extension of pyrene. The derivatives are highly fluorescent and feature low oxidation potentials. Using electrooxidation, crystals of cationic mixed-valence (MV) complexes were grown in which the organic salts organize into face-to-face π-stacks, a favorable solid-state arrangement for organic electronics. Variable-temperature electron paramagnetic resonance (EPR) measurements and relaxation studies suggest a strong electron delocalization along the longitudinal axis of the columnar π-stacking architectures. Electric measurements of single crystals of the MV salts show a semiconducting behavior with a remarkably high conductivity at room temperature. These findings support the notion that π-extension of heteroatom-doped polycyclic aromatic hydrocarbons is an attractive approach to fabricate nanographenes with a broad spectrum of semiconducting properties and high charge mobilities. 相似文献
Metal–organic frameworks (MOFs) with long-term stability and reversible high water uptake properties can be ideal candidates for water harvesting and indoor humidity control. Now, a mesoporous and highly stable MOF, BIT-66 is presented that has indoor humidity control capability and a photocatalytic bacteriostatic effect. BIT-66 (V3(O)3(H2O)(BTB)2), possesses prominent moisture tunability in the range of 45–60 % RH and a water uptake and working capacity of 71 and 55 wt %, respectively, showing good recyclability and excellent performance in water adsorption–desorption cycles. Importantly, this MOF demonstrates a unique photocatalytic bacteriostatic behavior under visible light, which can effectively ameliorate the bacteria and/or mold breeding problem in water adsorbing materials. 相似文献
HCHO has been confirmed as an active intermediate in the methanol-to-hydrocarbon (MTH) reaction, and is critical for interpreting the mechanisms of coke formation. Here, HCHO was detected and quantified during the MTH process over HSAPO-34 and HZSM-5 by in situ synchrotron radiation photoionization mass spectrometry. Compared with conventional methods, excellent time-resolved profiles were obtained to study the formation and fate of HCHO, and other products during the induction, steady-state reaction, and deactivation periods. Similar formation trends of HCHO and methane, and their close correlation in yields suggest that they are derived from disproportionation of methanol at acidic sites. In the presence of Y2O3, the amount of HCHO changes, affecting the hydrogen-transfer processes of olefins into aromatics and aromatics into cokes. The yield of HCHO affects the aromatic-based cycle and the formation of ethylene, indicating that ethylene is mainly formed from the aromatic-based cycle. 相似文献
As a kind of photoluminescent material, CuI complexes have many advantages such as adjustable emission, variable structures, and low cost, attracting attention in many fields. In this work, two novel two-coordinate CuI-N-heterocyclic carbene complexes were synthesized, and they exhibit unique dual emission properties, fluorescence and phosphorescence. The crystal structure, packing mode, and photophysical properties under different conditions were systematically studied, proving the emissive mechanism to be the locally excited state of the carbazole group. Based on this mechanism, ultralong room-temperature phosphorescence (RTP) with a lifetime of 140 ms is achieved by selective deuteration of the carbazole group. These results deepen the understanding of the luminescence mechanism and design strategy for two-coordinate CuI complexes, and prove their potential in applications as ultralong RTP materials. 相似文献
Energy components used in solid rocket propellants are beneficial for improving the energy performance, and their thermal decomposition characteristics significantly affect the combustion properties of the propellants. As a kind of energetic material with both high energy and low sensitivity (impact and friction), 5, 5'-bistetrazole-1, 1'-diolate (TKX-50) can effectively improve the energy and safety characteristics of solid propellants. Burning catalyst is another important component of solid propellants, which can significantly improve the burning rate of the propellant and reduce the pressure exponent. Among various burning catalysts, nanoscale transition metal oxides can promote the thermal decomposition of the energetic component, thus enhancing the combustion properties of the solid propellant. However, the catalytic effects of nanoscale transition metal oxides with different morphologies on the thermal decomposition of TKX-50 have rarely been studied. Based on the excellent catalytic activity of Fe2O3 for TKX-50 thermal decomposition, nano-Fe2O3 particles with spherical and tubular microstructures were used for TKX-50 thermal decomposition. The Fe2O3 nanoparticles were successfully fabricated via the solvothermal method and characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS) analyses. The XRD, FT-IR, and XPS results confirmed the successful fabrication of spherical and tubular Fe2O3 samples. The SEM and TEM images showed that the spherical Fe2O3 samples are composed of agglomerated Fe2O3 nanoparticles with an average particle size of 110 nm. In addition, the average diameter and length of hollow tubular Fe2O3 nanoparticles are 120 nm and 200 nm, respectively. The catalytic activities of spherical and tubular Fe2O3 for TKX-50 decomposition were studied by thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) methods. The DSC and TG-DTG curves showed that both tubular and spherical Fe2O3 could effectively promote TKX-50 thermal decomposition. The first thermal decomposition peak temperature (TFDP) of TKX-50 was reduced by 36.5 K and 26.3 K in the presence of tubular and spherical Fe2O3, respectively, at 10 K·min−1. The activation energy (Ea) of TKX-50, determined by the iso-conversional method, was significantly reduced in the presence of both tubular and spherical Fe2O3. The results indicated that the microstructure of the catalyst has a significant effect on its catalytic performance for TKX-50 thermal decomposition, and that tubular Fe2O3 with hollow microstructure possesses better catalytic activity than spherical Fe2O3. The excellent catalytic activity of tubular Fe2O3 can be attributed to the hollow microstructure, which has more active sites for TKX-50 thermal decomposition. 相似文献