Enhancing Reduced Density Matrix Functional Theory Calculations by Coupling Orbital and Occupation Optimizations.

Reduced density matrix functional theory (RDMFT) calculations are usually implemented in a decoupled manner, where the orbital and occupation optimizations are repeated alternately. Typically, orbital updates are performed using the unitary optimization method, while occupations are optimized through the explicit-by-implicit (EBI) method. The EBI method addresses explicit constraints by incorporating implicit functions, effectively transforming constrained optimization scenarios into unconstrained minimizations. Although the unitary and EBI methods individually achieve robust performance in optimizing orbitals and occupations, respectively, the decoupled optimization methods often suffer from slow convergence and require dozens of alternations between the orbital and occupation optimizations. To address this issue, this work proposes a coupled optimization method that combines unitary and EBI optimizations to update orbitals and occupations simultaneously at each step. To achieve favorable convergence in coupled optimization using a simple first-order algorithm, an effective and efficient preconditioner and line search are further introduced. The superiority of the new method is demonstrated through numerous tests on different molecules, random initial guesses, different basis sets, and different functionals. It outperforms all decoupled optimization methods in terms of convergence speed, convergence results, and convergence stability. Even a large system like C60 can converge to 10-8 au in 154 iterations, which shows that the coupled optimization method can make RDMFT more practical and facilitate its wider application and further development.

Metal-free sulfonylation of quinoxalinones to access 2-sulfonyl-oxylated quinoxalines via oxidative O-S cross coupling.

The C2 sulfonylation of quinoxalinones via a metal-free oxidative S-O cross-coupling strategy for synthesizing 2-sulfonyloxylated quinoxalines is established. It effectively solved the long-standing problems in the C2 transformation of quinoxalinones via a metal-free oxidative O-S coupling strategy. Compared with the traditional C2 transformed quinoxalinones-C2 chlorination method, this protocol is mild, facile, and environmentally friendly and exhibits good atomic economy and excellent functional group tolerance. Moreover, the utility of this methodology and the sulfonyloxyl handles was demonstrated through the synthesis of 2-substituted quinoxaline-based bioactive molecules.

Explicit-by-Implicit Treatment of Natural Orbital Occupations Using First- and Second-Order Optimization Algorithms: A Comparative Study.

To address the convergence issues in the natural occupation optimization of reduced density matrix functional theory (RDMFT), we recently proposed the explicit-by-implicit (EBI) idea to handle the ensemble N-representability constraint (Yao et al. J. Phys. Chem. Lett. 2021, 12, 6788). This work continues to focus on these issues that can affect the reliability of the electronic structure description in RDMFT; further explores the combination of EBI, as well as the (augmented) Lagrangian methods (both LM and ALM), with both first- and second-order numerical optimization algorithms; and carefully evaluates their performances in natural occupation optimizations of various systems, including strongly correlated systems and large molecules. By comparing both converged energies and elapsed times, it can be seen that the LM and ALM have serious convergence issues for systems of different sizes. In contrast, the optimizations of EBI can converge to better energies with fewer iterations. However, due to the local convergence nature of the Newton's Method (NM) algorithm, EBI@NM still suffers from the local minimum issue for both strongly correlated systems and large molecules. Overall, the combination of EBI with the simple first-order algorithm of gradient descent (GD), namely EBI@GD, consistently provides the lowest converged energies for different types of systems, with the lowest computational scaling. These tests demonstrate the advantages of EBI in the calculations of transition states, strongly correlated systems, and large molecules. Meanwhile, the insights gained from this work are helpful to further develop more efficient algorithms for RDMFT.

First-principles theoretical study on dry reforming of methane over perfect and boron-vacancy-containing h-BN sheet-supported Ni catalysts.

The entire reaction mechanism of the dry reforming of methane (DRM) as well as the competition processes over perfect and boron-vacancy-containing h-BN sheet-supported Ni-catalysts (labeled Ni2/h-BN and Ni2/h-BN-B-D) was studied by density functional theory calculations in the present work. Our calculation results show that B-defected h-BN strongly binds to the Ni2 active sites (i.e., shows a strong metal-support interaction (SMSI) character) due to the better electron transfer between Ni2 sites and the support. It was found that CH4 is easier to activate than molecular CO2. The activation of CO2 occurs on the surface of Ni2/h-BN through a direct route, whereas it is prone to follow a hydrogen-assisted path for Ni2/h-BN-B-D via the COOH* intermediate, and the results show that the oxidant O* is easily formed on the surface of Ni2/h-BN-B-D. It was also found that O* is the main oxidant agent for CHx* intermediates through the CH3-O oxidation mechanism. The reaction kinetic analysis indicated that the reverse water gas shift reaction (RWGS) is much more favorable than DRM (1.30 vs. 1.72 eV) over the Ni2/h-BN system, whereas the RWGS and DRM are comparable on Ni2/h-BN-B-D (1.77 vs. 1.66 eV), suggesting a high DRM activity on Ni2/h-BN-B-D. Moreover, neither methane cracking nor a Boudouard reaction to form C* species is thermodynamically and kinetically unfavorable over Ni2/h-BN-B-D; hence, Ni2/h-BN-B-D has strong resistance to carbon deposition. Compared to Ni(111), both Ni2/h-BN-B-D and Ni2/h-BN show strong resistance to carbon deposition. Our results provide a further mechanistic understanding of the DRM over an Ni-based catalyst through the SMSI characteristic and the SMSI favors strong resistance to carbon deposition.

[The Relationship between Speed of Platelet Recovery and Its R-squared and Efficacy after First Induction Chemotherapy in Acute Myeloid Leukemia].

OBJECTIVE: To calculate the cut-off values of speed of platelet recovery and its R-squared in patients with acute myeloid leukemia (AML) after initial induction chemotherapy, which were used to predict the complete remission (CR) of the first induction chemotherapy, and guide the clinic to choose the next appropriate chemotherapy regimen as soon as possible. METHODS: A total of 117 patients with newly diagnosed AML in the Second Hospital of Shanxi Medical University were included. Patients were diagnosed by morphology, immunology, cytogenetics, and molecular biology (MICM) classification, and the risk stratification was evaluated in combination with the clinical situations of the patients at the time of admission. The peripheral platelet counts after the first induction chemotherapy were detected and the linear regression equation was used to calculate the recovery speed of platelet counts in 5 consecutive blood cell analysis before discharge. According to the ROC curve, the cut-off value between the recovery speed and the R-squared was calculated, and the cut-off value was used to divide the patients into different groups. The differences between groups were compared by Pearson χ2 test to observe the remission effect of the first induction chemotherapy. RESULTS: ROC curve analysis showed that the cut-off value for predicting the platelet recovery speed and its R-squared of the first induction chemotherapy to achieve remission was 4.059 5×109/(L·d) and 72.7%, the sensitivity was 77% and 63.9%, the specificity was 62.5% and 67.9%, and the Youden index was 0.395 and 0.318, respectively. The patients were divided into different groups and compared according to the above cut-off values, and the results showed statistical differences (P<0.001, P=0.001). CONCLUSION: The cut-off value of platelet recovery speed and its R-squared after the first induction chemotherapy calculated by peripheral platelet count and ROC curve in AML patients can be used as an index to evaluate the remission. The faster the platelet recovery speed after chemotherapy is, the more likely patients achieve remission. The more stable the platelet recovery tendency is, the more likely patients achieve remission too.

Handling Ensemble N-Representability Constraint in Explicit-by-Implicit Manner.

The convergence issues caused by the improper treatment of the ensemble N-representability constraint have severely affected the applicability and reproducibility of reduced density matrix functional theory (RDMFT). Unlike the commonly used Lagrange methods explicitly bringing the constraint into the objective functions, we present a different idea to handle the constraint in an implicit manner, which is achieved by introducing implicit functions to exactly consider the nonlinear unclear connection embedded in the explicit constraint. This explicit-by-implicit idea, denoted as EBI, thus transforms the constrained optimization problem into an unconstrained minimization problem. The tests on different systems, initial guesses, and functionals demonstrate the superiority of EBI in the treatment of the ensemble N-representability constraint. Therefore, EBI solves the convergence issues of the Lagrange methods, which is essential for further development and application of RDMFT. Besides, the idea of EBI is helpful for the treatment of different constrained problems in modern physics and chemistry.

[Therapeutic Effect of Spleen Low Molecular Weight Extracts on Leukopenia Caused by Epirubicin in Mice and Its Mechanism].

OBJECTIVE: To investigate the therapeutic effect of spleen low molecular weight extracts on epileptics hydrochloride-induced leukopenia in mice and explore its mechanism. METHODS: The model of leukopenia in mice was established by the injection of epirubicin hydrochloride (10 mg/kg). After the injection of chemotherapeutic drugs, leukocytopenia mice were treated with different doses of spleen low molecular weight extract, Ganoderma oral solution and recombinant granulocyte colony stimulating factor (rhG-CSF). The general survival status indicators such as body weight, coat color and athletic ability of mice in each group were recorded; the tail vein blood of mice in each group was collected and the white blood cell count in them was calculated; bone marrow of mice was taken and bone marrow smears were observed. RESULTS: In the model group, the weight of the mice gradually decreased in the later period, their coat became dark and rough, and the ability to exercise decreased, while the mice in the treatment groups showed different degrees of improvement in their survival status except for the mice treated by rhG-CSF. There was no significant fluctuation in the white blood cell count of the blank control mice. After injection of epirubicin, the white blood cell count of peripheral blood in the model mice and treated mice were decreased. The white blood cell count was lower in the mice treated with high-dose low molecular weight extract and rhG-CSF than that in other experimental groups. Bone marrow smear showed that the proportion of bone marrow nucleated cells in the mice treated with the low molecular weight extract of the spleen was significantly higher than that of model mice (P<0.05). CONCLUSION: The low molecular weight spleen extracts can significantly improve the hematopoietic state of mouse bone marrow, promote the proliferation of inhibited bone marrow cells, and thus has the effect of treating leukopenia in mice.