以Van Der Waals力作用半径为边界条件,构建了煤大分子骨架模型及煤对CH4吸附的量子动力学模型;采用量子化学DFT方法,在6-311G++基组上对煤大分子骨架模型及煤对CH4分子吸附模型结构进行了优化,得到了多种吸附平衡态的几何构型以及吸附...以Van Der Waals力作用半径为边界条件,构建了煤大分子骨架模型及煤对CH4吸附的量子动力学模型;采用量子化学DFT方法,在6-311G++基组上对煤大分子骨架模型及煤对CH4分子吸附模型结构进行了优化,得到了多种吸附平衡态的几何构型以及吸附的稳定平衡结构;通过煤大分子骨架模型的Mulliken Atomic Charges分析,研究了煤分子对CH4分子的吸附中心,吸附位能曲线,以及CH4分子键长键角的变化。展开更多
Knowledge of the soil water characteristic curve is fundamental for understanding unsaturated soils.The objective of this work was to find scanning hysteresis loops of two fine textured soils at water potentials below...Knowledge of the soil water characteristic curve is fundamental for understanding unsaturated soils.The objective of this work was to find scanning hysteresis loops of two fine textured soils at water potentials below wilting point.This was done by equilibration over NaCl solutions with water potentials of-6.6 to-18.8 MPa at 25℃.When cycled repeatedly through a series of potentials in the range noted previously both soils exhibited a hysteresis effect.The experimental differences in water content between the drying and wetting soils at the same water potential were much too large to be accounted for by failure to allow sufficient time to attain equilibrium as predicted by the exponential decay model.The wetting versus drying differences were relatively small,however,at only 4 mg g-1 or less in absolute terms and about 3% of the mean of wetting and drying,in relative terms.Hysteresis should be a consideration when modeling biological and physical soil processes at water contents below the wilting point,where small differences in water content result in large potential energy changes.展开更多
文摘以Van Der Waals力作用半径为边界条件,构建了煤大分子骨架模型及煤对CH4吸附的量子动力学模型;采用量子化学DFT方法,在6-311G++基组上对煤大分子骨架模型及煤对CH4分子吸附模型结构进行了优化,得到了多种吸附平衡态的几何构型以及吸附的稳定平衡结构;通过煤大分子骨架模型的Mulliken Atomic Charges分析,研究了煤分子对CH4分子的吸附中心,吸附位能曲线,以及CH4分子键长键角的变化。
文摘Knowledge of the soil water characteristic curve is fundamental for understanding unsaturated soils.The objective of this work was to find scanning hysteresis loops of two fine textured soils at water potentials below wilting point.This was done by equilibration over NaCl solutions with water potentials of-6.6 to-18.8 MPa at 25℃.When cycled repeatedly through a series of potentials in the range noted previously both soils exhibited a hysteresis effect.The experimental differences in water content between the drying and wetting soils at the same water potential were much too large to be accounted for by failure to allow sufficient time to attain equilibrium as predicted by the exponential decay model.The wetting versus drying differences were relatively small,however,at only 4 mg g-1 or less in absolute terms and about 3% of the mean of wetting and drying,in relative terms.Hysteresis should be a consideration when modeling biological and physical soil processes at water contents below the wilting point,where small differences in water content result in large potential energy changes.
