We investigate the structural and elastic properties of γ TiAl under high pressures using the norm-conservingpseudopotentials within the local density approximation(LDA)in the frame of density functional theory.The c...We investigate the structural and elastic properties of γ TiAl under high pressures using the norm-conservingpseudopotentials within the local density approximation(LDA)in the frame of density functional theory.The calculatedpressure dependence of the elastic constants is in excellent agreement with the experimental results.The elastic constantsand anisotropy as a function of applied pressure are presented.Through the quasi-harmonic Debye model,we alsoinvestigate the thermodynamic properties of γ TiAl.展开更多
The line intensities of 001-000 transition of the asymptotic asymmetric-top 03 molecule at several tem- peratures are calculated by directly calculating the partition functions and regarding the rotationless transitio...The line intensities of 001-000 transition of the asymptotic asymmetric-top 03 molecule at several tem- peratures are calculated by directly calculating the partition functions and regarding the rotationless transition dipole moment squared as a constant.The calculated values of the total internal partition sums (TIPS) are consistent with the data of HITRAN database with -0.61% at 296 K.The calculated line intensity data at 500 K and 3000 K are also in excellent agreement with the data in HITRAN database with less than 0.659% and 5.458% at 500 K and 3000 K, which provide a strong support for the calculations of partition function and line intensity at high temperature.Then we extend the calculation to higher temperatures.The line intensities and simulated spectra of v_3 band of the asymptotic asymmetric-top O_3 molecule at 4000 and 5000 K are reported.The results are of significance for the studying of the molecular high-temperature spectrum including experimental measurements and theoretical calculations.展开更多
Density functional theory (DFT) was used to calculate a set of molecular descri ptors (properties) for 14 fluoroquinolones with anti-B.fragilis activity. Principal component analysis (PCA) and hierarchical clust...Density functional theory (DFT) was used to calculate a set of molecular descri ptors (properties) for 14 fluoroquinolones with anti-B.fragilis activity. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were employed in order to reduce dimensionality and investigate which subset of variables should be more effective for classifying fluoroquinolones according to their an-B.fragilis activity degree. The PCA shows that the variables of ELUMO, AEHL, μ, Q2, Q3, Q5, Q6, QB, LogP, MR and MP are responsible for the separation between compounds with higher and lower anti-B.fragilis activities. The HCA results are similar to those obtained with PCA. By using the chemometric results, 4 synthetic compounds were analyzed through PCA and HCA, and 2 of them are proposed as active molecules against B.fragilis, which is consistent with the results of clinic experiments. The methodologies of PCA and HCA provide a reliable rule for classifying new fluoroquinolones with anti-B.fragilis activity.展开更多
相片吸收系列为 Si <SUB 被计算了 > n </SUB> 和 Si <SUB > n </SUB > O (n ≤
5 ) 簇使用时间依赖者密度功能理论。我们的研究建议那 Si <SUB > n 1 </SUB > O 簇是比相应 Si <SUB ...相片吸收系列为 Si <SUB 被计算了 > n </SUB> 和 Si <SUB > n </SUB > O (n ≤
5 ) 簇使用时间依赖者密度功能理论。我们的研究建议那 Si <SUB > n 1 </SUB > O 簇是比相应 Si <SUB 的那些相对稳定的 > n </SUB> 簇。而且,实质的差别在精力区域在不同分子的吸收系列之中被观察(0 ~ 8 eV ) 。比较二个不同交换关联潜力,本地密度、概括坡度的近似,两计算光光谱介绍一样光谱特征。展开更多
This paper applies the multiple ellipsoid model to the 16Ne (20Ne, 28Ne, 34Ne)-Na2 collision systems, and calcu- lates integral cross sections for rotational excitation at the incident energy of 190 meV. It can be s...This paper applies the multiple ellipsoid model to the 16Ne (20Ne, 28Ne, 34Ne)-Na2 collision systems, and calcu- lates integral cross sections for rotational excitation at the incident energy of 190 meV. It can be seen that the accuracy of the integral cross sections can be improved by increasing the number of equipotential ellipsoid surfaces. Moreover, by analysing the differences of these integral cross sections, it obtains the change rules of the integral cross sections with the increase of rotational angular quantum number j', and with the change of the mass of isotope substitution neon atom. Finally, the contribution of different regions of the potential to inelastic cross sections for 20Ne-Na2 collision system is investigated at relative incident energy of 190 meV.展开更多
We report on the calculations of transition wavelengths and weighted oscillator strengths for 2s22p^6 2s2p^6np (4 〈 n 〈 20) electric dipole (El) transitions of Cu^19+ ion. The flexible atomic code (FAC) has b...We report on the calculations of transition wavelengths and weighted oscillator strengths for 2s22p^6 2s2p^6np (4 〈 n 〈 20) electric dipole (El) transitions of Cu^19+ ion. The flexible atomic code (FAC) has been adopted for the calculations. Comparisons are made with the experimental data available, showing that the present results for 4 〈 n 〈 6 are more accurate than the previous calculated values. Furthermore, combining the quantum defect theory (QDT) with the transition energies of 2s^22p^62s2p^6np, the quantum defects for 2s2p^6np Rydberg series of Cu^19+ ion are determined. In addition, the energies of any highly excited states (n 〉 20) for this series can be reliably predicted using the QDT and the given quantum defects. The ionization energies for Cu^19+ and Cu^20+ ions are also calculated and they excellently accord with previous experimental and calculated values.展开更多
The potential energies of H2 molecules with partially truncated and open cage C_(60) fullerenes,including C_(58),C_(55),C_(54)(I),C54(II)and C_(46),are investigated by means of the density functional theory method.The...The potential energies of H2 molecules with partially truncated and open cage C_(60) fullerenes,including C_(58),C_(55),C_(54)(I),C54(II)and C_(46),are investigated by means of the density functional theory method.The energy barrier for one H2 molecule(with two postures)entering into the nanocage decreases from 435.59(513.45)kcal/mol to 3.64(¡2.06)kcal/mol with the increase of the truncated pore.The grand canonical Monte Carlo simulations reveal that each nanocage can accommodate only one H_(2) molecule inside its cavity at both 77K and 298 K.All the other H2 molecules are adsorbed round the truncated pores outside the nanocages.Exceptionally,the truncated C_(46) can store 2.28wt%H2 molecules at 77 K.Therefore,the truncating part of the C60 molecule may be a novel idea to explore C_(60) fullerene as a hydrogen storage material.展开更多
Orbital responses to methyl sites in CnH2n+2 (n = 1-6) are studied by B3LYP/TZVP based on the most stable geometries using the B3LYP/aug-cc-pVTZ method. Vertical ionization energies are produced using the SAOP/et-p...Orbital responses to methyl sites in CnH2n+2 (n = 1-6) are studied by B3LYP/TZVP based on the most stable geometries using the B3LYP/aug-cc-pVTZ method. Vertical ionization energies are produced using the SAOP/et-pVQZ model for the complete valence space. The highest occupied molecular orbital (HOMO) investigations indicate the p- electron profiles in methane, ethane, propane, and n-butane. By increasing the number of carbon-carbon bonds in lower momentum regions, the s, p-hybridized orbitals are built and display strong exchange and correlation interactions in lower momentum space (P 〈 0.50 a.u.). Meanwhile, the relative intensities of the isomers in lower momentum space show the strong bonding number dependence of the carbon-carbon bonds, meaning that more electrons have contributed to orbital construction. The study of representative valence orbital momentum distribution further confirms that the structural changes lead to evident electronic rearrangement over the whole valence space. An analysis based on the isomers reveals that the valence orbitals are isomer-dependent and the valence ionization energy experiences an apparent shift in the inner valence space. However, such shifts are greatly reduced in the outer valence space. Meanwhile, the opposite energy shift trend is found in the intermediate valence space.展开更多
Density functional theory (DFT) was used to calculate a set of molecular descriptors (properties) for 14 TIBO derivatives with anti-HIV activity. Principal component analysis (PCA) and hierarchical cluster analy...Density functional theory (DFT) was used to calculate a set of molecular descriptors (properties) for 14 TIBO derivatives with anti-HIV activity. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were employed in order to reduce dimensionality and investigate which subset of variables should be more effective for classifying TIBO derivatives according to their degree of anti-HIV activity. The PCA showed that the EHOMO, μ, LogP, QA, QB and MR variables are responsible for the separation between compounds with higher and lower anti-HIV activity. The HCA results are similar to those obtained with PCA. By using the chemometric results, four synthetic compounds were analyzed through PCA and HCA and three of them are proposed as active molecules against HIV, which is consistent with the results of clinic experiments. The methodologies of PCA and HCA provide a reliable rule for classifying new TIBO derivatives with anti-HIV activity. The model obtained showed not only statistical significance but also predictive ability.展开更多
基金The project supported by National Natural Science Foundation of China under Grant No. 10676025, and the Research Fund for the Doctoral Program of High Education of China under Grant No. 20050610010
基金National Natural Science Foundation of China under Grant Nos.10376021 and 10274055the Research Fund for the Doctoral Program of High Education of China under Grant No.20020610001
文摘We investigate the structural and elastic properties of γ TiAl under high pressures using the norm-conservingpseudopotentials within the local density approximation(LDA)in the frame of density functional theory.The calculatedpressure dependence of the elastic constants is in excellent agreement with the experimental results.The elastic constantsand anisotropy as a function of applied pressure are presented.Through the quasi-harmonic Debye model,we alsoinvestigate the thermodynamic properties of γ TiAl.
基金supported by National Natural Science Foundation of China under Grant No.10574096the Major Program for Basic Research of National Security of China under Grant No.5134202-04the Natural Science Foundation of the Bureau of Education of Guizhou Province under Grant No.2006204
文摘The line intensities of 001-000 transition of the asymptotic asymmetric-top 03 molecule at several tem- peratures are calculated by directly calculating the partition functions and regarding the rotationless transition dipole moment squared as a constant.The calculated values of the total internal partition sums (TIPS) are consistent with the data of HITRAN database with -0.61% at 296 K.The calculated line intensity data at 500 K and 3000 K are also in excellent agreement with the data in HITRAN database with less than 0.659% and 5.458% at 500 K and 3000 K, which provide a strong support for the calculations of partition function and line intensity at high temperature.Then we extend the calculation to higher temperatures.The line intensities and simulated spectra of v_3 band of the asymptotic asymmetric-top O_3 molecule at 4000 and 5000 K are reported.The results are of significance for the studying of the molecular high-temperature spectrum including experimental measurements and theoretical calculations.
基金The project was supported by the National Natural Science Foundation of China (No. 10574096)
文摘Density functional theory (DFT) was used to calculate a set of molecular descri ptors (properties) for 14 fluoroquinolones with anti-B.fragilis activity. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were employed in order to reduce dimensionality and investigate which subset of variables should be more effective for classifying fluoroquinolones according to their an-B.fragilis activity degree. The PCA shows that the variables of ELUMO, AEHL, μ, Q2, Q3, Q5, Q6, QB, LogP, MR and MP are responsible for the separation between compounds with higher and lower anti-B.fragilis activities. The HCA results are similar to those obtained with PCA. By using the chemometric results, 4 synthetic compounds were analyzed through PCA and HCA, and 2 of them are proposed as active molecules against B.fragilis, which is consistent with the results of clinic experiments. The methodologies of PCA and HCA provide a reliable rule for classifying new fluoroquinolones with anti-B.fragilis activity.
基金supported by the National Natural Science Foundation of China and China Academy of Engineering Physics under Grant No. 10676025 (NSAF)
文摘相片吸收系列为 Si <SUB 被计算了 > n </SUB> 和 Si <SUB > n </SUB > O (n ≤
5 ) 簇使用时间依赖者密度功能理论。我们的研究建议那 Si <SUB > n 1 </SUB > O 簇是比相应 Si <SUB 的那些相对稳定的 > n </SUB> 簇。而且,实质的差别在精力区域在不同分子的吸收系列之中被观察(0 ~ 8 eV ) 。比较二个不同交换关联潜力,本地密度、概括坡度的近似,两计算光光谱介绍一样光谱特征。
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10974139 and 10964002), the Doctoral Program Foundation of Institution of Higher Education of China (Grant No. 20050610010), the Science Technology Foundation of Guizhou Province of China (Grant No. [2009]2066) and Project of Aiding Elites' Research Condition of Guizhou Province (Grant No. TZJF-2008-42).
文摘This paper applies the multiple ellipsoid model to the 16Ne (20Ne, 28Ne, 34Ne)-Na2 collision systems, and calcu- lates integral cross sections for rotational excitation at the incident energy of 190 meV. It can be seen that the accuracy of the integral cross sections can be improved by increasing the number of equipotential ellipsoid surfaces. Moreover, by analysing the differences of these integral cross sections, it obtains the change rules of the integral cross sections with the increase of rotational angular quantum number j', and with the change of the mass of isotope substitution neon atom. Finally, the contribution of different regions of the potential to inelastic cross sections for 20Ne-Na2 collision system is investigated at relative incident energy of 190 meV.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11074176 and 11064007)
文摘We report on the calculations of transition wavelengths and weighted oscillator strengths for 2s22p^6 2s2p^6np (4 〈 n 〈 20) electric dipole (El) transitions of Cu^19+ ion. The flexible atomic code (FAC) has been adopted for the calculations. Comparisons are made with the experimental data available, showing that the present results for 4 〈 n 〈 6 are more accurate than the previous calculated values. Furthermore, combining the quantum defect theory (QDT) with the transition energies of 2s^22p^62s2p^6np, the quantum defects for 2s2p^6np Rydberg series of Cu^19+ ion are determined. In addition, the energies of any highly excited states (n 〉 20) for this series can be reliably predicted using the QDT and the given quantum defects. The ionization energies for Cu^19+ and Cu^20+ ions are also calculated and they excellently accord with previous experimental and calculated values.
基金by the National Natural Science Foundation of China under Grant Nos 11074176 and 10976019the Research Fund for the Doctoral Program of Higher Education of China under Grant No 20100181110080.
文摘The potential energies of H2 molecules with partially truncated and open cage C_(60) fullerenes,including C_(58),C_(55),C_(54)(I),C54(II)and C_(46),are investigated by means of the density functional theory method.The energy barrier for one H2 molecule(with two postures)entering into the nanocage decreases from 435.59(513.45)kcal/mol to 3.64(¡2.06)kcal/mol with the increase of the truncated pore.The grand canonical Monte Carlo simulations reveal that each nanocage can accommodate only one H_(2) molecule inside its cavity at both 77K and 298 K.All the other H2 molecules are adsorbed round the truncated pores outside the nanocages.Exceptionally,the truncated C_(46) can store 2.28wt%H2 molecules at 77 K.Therefore,the truncating part of the C60 molecule may be a novel idea to explore C_(60) fullerene as a hydrogen storage material.
基金supported by the National Natural Science Foundation of China (Grant Nos.10974139,11104247,and 11176020)
文摘Orbital responses to methyl sites in CnH2n+2 (n = 1-6) are studied by B3LYP/TZVP based on the most stable geometries using the B3LYP/aug-cc-pVTZ method. Vertical ionization energies are produced using the SAOP/et-pVQZ model for the complete valence space. The highest occupied molecular orbital (HOMO) investigations indicate the p- electron profiles in methane, ethane, propane, and n-butane. By increasing the number of carbon-carbon bonds in lower momentum regions, the s, p-hybridized orbitals are built and display strong exchange and correlation interactions in lower momentum space (P 〈 0.50 a.u.). Meanwhile, the relative intensities of the isomers in lower momentum space show the strong bonding number dependence of the carbon-carbon bonds, meaning that more electrons have contributed to orbital construction. The study of representative valence orbital momentum distribution further confirms that the structural changes lead to evident electronic rearrangement over the whole valence space. An analysis based on the isomers reveals that the valence orbitals are isomer-dependent and the valence ionization energy experiences an apparent shift in the inner valence space. However, such shifts are greatly reduced in the outer valence space. Meanwhile, the opposite energy shift trend is found in the intermediate valence space.
基金The project was supported by the National Natural Science Foundation of China (No. 10574096)
文摘Density functional theory (DFT) was used to calculate a set of molecular descriptors (properties) for 14 TIBO derivatives with anti-HIV activity. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were employed in order to reduce dimensionality and investigate which subset of variables should be more effective for classifying TIBO derivatives according to their degree of anti-HIV activity. The PCA showed that the EHOMO, μ, LogP, QA, QB and MR variables are responsible for the separation between compounds with higher and lower anti-HIV activity. The HCA results are similar to those obtained with PCA. By using the chemometric results, four synthetic compounds were analyzed through PCA and HCA and three of them are proposed as active molecules against HIV, which is consistent with the results of clinic experiments. The methodologies of PCA and HCA provide a reliable rule for classifying new TIBO derivatives with anti-HIV activity. The model obtained showed not only statistical significance but also predictive ability.