Conventional error cancellation approaches separate molecules into smaller fragments and sum the errors of all fragments to counteract the overall computational error of the parent molecules.However,these approaches m...Conventional error cancellation approaches separate molecules into smaller fragments and sum the errors of all fragments to counteract the overall computational error of the parent molecules.However,these approaches may be ineffective for systems with strong localized chemical effects,as fragmenting specific substructures into simpler chemical bonds can introduce additional errors instead of mitigating them.To address this issue,we propose the Substructure-Preserved Connection-Based Hierarchy(SCBH),a method that automatically identifies and freezes substructures with significant local chemical effects prior to molecular fragmentation.The SCBH is validated by the gas-phase enthalpy of formation calculation of CHNO molecules.Therein,based on the atomization scheme,the reference and test values are derived at the levels of Gaussian-4(G4)and M062X/6-31+G(2df,p),respectively.Compared to commonly used approaches,SCBH reduces the average computational error by half and requires only15%of the computational cost of G4 to achieve comparable accuracy.Since different types of local effect structures have differentiated influences on gas-phase enthalpy of formation,substituents with strong electronic effects should be retained preferentially.SCBH can be readily extended to diverse classes of organic compounds.Its workflow and source code allow flexible customization of molecular moieties,including azide,carboxyl,trinitromethyl,phenyl,and others.This strategy facilitates accurate,rapid,and automated computations and corrections,making it well-suited for high-throughput molecular screening and dataset construction for gas-phase enthalpy of formation.展开更多
Zabuye Saline Lake, Tibet, China, is unrivalled in the world for its very high salinity, in particular, for the very high concentration of ions of lithium, potassium, and boron in the brine. It belongs to alkaline and...Zabuye Saline Lake, Tibet, China, is unrivalled in the world for its very high salinity, in particular, for the very high concentration of ions of lithium, potassium, and boron in the brine. It belongs to alkaline and carbonate borate type salt lake. As a part of the study on phase equilibrium of the 6 component subsystem Li +, Na +, K +/Cl -, CO 2- 3, B 4O 2- 7 H 2O of the brine system, a study on the reciprocal quaternary system Li +, K +/Cl -, CO 2- 3 H 2O at 298 K was done with isothermal dissolution equilibrium method in the present work. The phase equilibrium of the reciprocal quaternary system Li +, K +/Cl -, CO 2- 3 H 2O at 298 K was studied with isothermal dissolution method in this work. The physico chemistry properties of the corresponding equilibrium solutions such as densities, viscosities, refractive index, conductivities and pH value were determined. The dried salt diagram of the system consists of four crystallization fields (KCl, Li 2CO 3, LiCl·H 2O, K 2CO 3·3/2H 2O) and five isothermal solubility curves. There are no double slat or solid solution found. Pitzers model of the electrolyte solution theory was used for parameterization from the results of solubility determination for subsystems and the prediction of solubilities for the reciprocal quaternary system was made. The solubility data of the experiment are in agreement with those calculated. [WT5HZ]展开更多
基金the support of the National Natural Science Foundation of China(22575230)。
文摘Conventional error cancellation approaches separate molecules into smaller fragments and sum the errors of all fragments to counteract the overall computational error of the parent molecules.However,these approaches may be ineffective for systems with strong localized chemical effects,as fragmenting specific substructures into simpler chemical bonds can introduce additional errors instead of mitigating them.To address this issue,we propose the Substructure-Preserved Connection-Based Hierarchy(SCBH),a method that automatically identifies and freezes substructures with significant local chemical effects prior to molecular fragmentation.The SCBH is validated by the gas-phase enthalpy of formation calculation of CHNO molecules.Therein,based on the atomization scheme,the reference and test values are derived at the levels of Gaussian-4(G4)and M062X/6-31+G(2df,p),respectively.Compared to commonly used approaches,SCBH reduces the average computational error by half and requires only15%of the computational cost of G4 to achieve comparable accuracy.Since different types of local effect structures have differentiated influences on gas-phase enthalpy of formation,substituents with strong electronic effects should be retained preferentially.SCBH can be readily extended to diverse classes of organic compounds.Its workflow and source code allow flexible customization of molecular moieties,including azide,carboxyl,trinitromethyl,phenyl,and others.This strategy facilitates accurate,rapid,and automated computations and corrections,making it well-suited for high-throughput molecular screening and dataset construction for gas-phase enthalpy of formation.
文摘Zabuye Saline Lake, Tibet, China, is unrivalled in the world for its very high salinity, in particular, for the very high concentration of ions of lithium, potassium, and boron in the brine. It belongs to alkaline and carbonate borate type salt lake. As a part of the study on phase equilibrium of the 6 component subsystem Li +, Na +, K +/Cl -, CO 2- 3, B 4O 2- 7 H 2O of the brine system, a study on the reciprocal quaternary system Li +, K +/Cl -, CO 2- 3 H 2O at 298 K was done with isothermal dissolution equilibrium method in the present work. The phase equilibrium of the reciprocal quaternary system Li +, K +/Cl -, CO 2- 3 H 2O at 298 K was studied with isothermal dissolution method in this work. The physico chemistry properties of the corresponding equilibrium solutions such as densities, viscosities, refractive index, conductivities and pH value were determined. The dried salt diagram of the system consists of four crystallization fields (KCl, Li 2CO 3, LiCl·H 2O, K 2CO 3·3/2H 2O) and five isothermal solubility curves. There are no double slat or solid solution found. Pitzers model of the electrolyte solution theory was used for parameterization from the results of solubility determination for subsystems and the prediction of solubilities for the reciprocal quaternary system was made. The solubility data of the experiment are in agreement with those calculated. [WT5HZ]
