With replacement of N atoms by CH groups in the most stable cycled N4H4 molecules,twelve possible isomers of Nn(CH)4-nH4 have been designed and optimized at the B3LYP/6-311++G level of theory.The vibrational frequenci...With replacement of N atoms by CH groups in the most stable cycled N4H4 molecules,twelve possible isomers of Nn(CH)4-nH4 have been designed and optimized at the B3LYP/6-311++G level of theory.The vibrational frequencies were calculated at the same level of theory.The structures and properties were analyzed with the natural bond orbital(NBO) and the atoms in molecules(AIM)theory.Meanwhile,the dipole moments and the energy have been discussed.The results indicate that stabilities of these isomers increase with more CH groups replacements of N4H4 due to decrements of their densities of energies.The G3B3 calculations show that the isomers have high heat of formations(HOFs)and higher density of energies,which indicate them maybe a kind of potential and novel energetic material.展开更多
采用密度泛函理论的b3lyp方法在6-311++G**基组上对30种N8H8链状异构体进行了理论计算,并应用分子中的原子理论(Atoms In Molecules,AIM)和自然键轨道理论(Nature Bond Orbital,NBO)分析了这些化合物相对稳定性和成键特征,G3MP2方法计...采用密度泛函理论的b3lyp方法在6-311++G**基组上对30种N8H8链状异构体进行了理论计算,并应用分子中的原子理论(Atoms In Molecules,AIM)和自然键轨道理论(Nature Bond Orbital,NBO)分析了这些化合物相对稳定性和成键特征,G3MP2方法计算了各异构体的能量及生成热。结果表明:N8H8链状异构体中,含有N=N双键特征的异构体稳定性较好,影响氮氮键键长变化的主要因素是N原子孤对电子到相邻的氮氮键的超共轭作用;所有异构体中α3的生成热最大,β15的密度最大。展开更多
采用三维全息原子场作用矢量（3D-HoVAIF）研究89个四氢咪唑苯二氮卓酮（TIBO）类抗艾滋病药物的定量构效关系（QSAR）。分别运用偏最小二乘回归、人工神经网络建模，同时采用内部及外部双重验证的办法深入分析和检验模型的稳定性。PLS...采用三维全息原子场作用矢量（3D-HoVAIF）研究89个四氢咪唑苯二氮卓酮（TIBO）类抗艾滋病药物的定量构效关系（QSAR）。分别运用偏最小二乘回归、人工神经网络建模，同时采用内部及外部双重验证的办法深入分析和检验模型的稳定性。PLS与ANN建模的复相关系数（Rcum^2）、留一法（1eave-one-out，LOO）交互校验（cross-validation，CV）复相关系数（Qcv^2）和外部样本校验复相关系数（Qext^2），分别为0．802、0．710、0．552和0．871、0．864、0．760。表明用3D-HoVAIF表征TIBO类抗艾滋病药物分子结构信息较好，建立QSAR模型的稳定性和预测能力良好，运用ANN建模优于PLS及前人报道的多元线性回归（multiple linear regression，MLR）。展开更多
文摘With replacement of N atoms by CH groups in the most stable cycled N4H4 molecules,twelve possible isomers of Nn(CH)4-nH4 have been designed and optimized at the B3LYP/6-311++G level of theory.The vibrational frequencies were calculated at the same level of theory.The structures and properties were analyzed with the natural bond orbital(NBO) and the atoms in molecules(AIM)theory.Meanwhile,the dipole moments and the energy have been discussed.The results indicate that stabilities of these isomers increase with more CH groups replacements of N4H4 due to decrements of their densities of energies.The G3B3 calculations show that the isomers have high heat of formations(HOFs)and higher density of energies,which indicate them maybe a kind of potential and novel energetic material.
文摘采用密度泛函理论的b3lyp方法在6-311++G**基组上对30种N8H8链状异构体进行了理论计算,并应用分子中的原子理论(Atoms In Molecules,AIM)和自然键轨道理论(Nature Bond Orbital,NBO)分析了这些化合物相对稳定性和成键特征,G3MP2方法计算了各异构体的能量及生成热。结果表明:N8H8链状异构体中,含有N=N双键特征的异构体稳定性较好,影响氮氮键键长变化的主要因素是N原子孤对电子到相邻的氮氮键的超共轭作用;所有异构体中α3的生成热最大,β15的密度最大。
文摘采用三维全息原子场作用矢量（3D-HoVAIF）研究89个四氢咪唑苯二氮卓酮（TIBO）类抗艾滋病药物的定量构效关系（QSAR）。分别运用偏最小二乘回归、人工神经网络建模，同时采用内部及外部双重验证的办法深入分析和检验模型的稳定性。PLS与ANN建模的复相关系数（Rcum^2）、留一法（1eave-one-out，LOO）交互校验（cross-validation，CV）复相关系数（Qcv^2）和外部样本校验复相关系数（Qext^2），分别为0．802、0．710、0．552和0．871、0．864、0．760。表明用3D-HoVAIF表征TIBO类抗艾滋病药物分子结构信息较好，建立QSAR模型的稳定性和预测能力良好，运用ANN建模优于PLS及前人报道的多元线性回归（multiple linear regression，MLR）。
