The reaction of laser-ablated vanadium, niobium and tantalum atoms with hydrogen sulfide has been investigated using matrix isolation FTIR and theoretical calculations. The metal atoms inserted into the H-S bond of H2...The reaction of laser-ablated vanadium, niobium and tantalum atoms with hydrogen sulfide has been investigated using matrix isolation FTIR and theoretical calculations. The metal atoms inserted into the H-S bond of H2S to form the HMSH molecules （M=V, Nb, Ta）, which rearranged to H2MS molecules on annealing for Nb and Ta. The HMSH molecule can also further react with another H2S to form the H2M（SH）2 molecules. These new molecules were identified on the basis of the D2S and H234S isotopic substitutions. DFT （B3LYP and BPW91） theoretical calculations are used to predict energies, geometries, and vibrational frequencies for these novel metal dihydrido complexes and molecules. Reaction mechanism for formation of group V dihydrido complex was investigated by DFT internal reaction coordinate calculations. The dissociation of HVSH gave VS＋H2 on broad band irradiation and reverse reaction happened on annealing. Based on B3LYP calculation releasing hydrogen from HVSH is endothermic only by 13.5 kcal/mol with lower energy barrier of 16.9 kcal/mol.展开更多
The bulk metal forming processes were simulated by using a one-step finite element(FE)approach based on deformation theory of plasticity,which enables rapid prediction of final workpiece configurations and stress/stra...The bulk metal forming processes were simulated by using a one-step finite element(FE)approach based on deformation theory of plasticity,which enables rapid prediction of final workpiece configurations and stress/strain distributions.This approach was implemented to minimize the approximated plastic potential energy derived from the total plastic work and the equivalent external work in static equilibrium,for incompressibly rigid-plastic materials,by FE calculation based on the extremum work principle.The one-step forward simulations of compression and rolling processes were presented as examples,and the results were compared with those obtained by classical incremental FE simulation to verify the feasibility and validity of the proposed method.展开更多
The density function theory at the B3LYP/6-31G＊ level was employed to study the structures, including the total energies （EZpE）, the geometries, the oxygen balances （OB100）, the dipole moments, of polynitrohexaaz...The density function theory at the B3LYP/6-31G＊ level was employed to study the structures, including the total energies （EZpE）, the geometries, the oxygen balances （OB100）, the dipole moments, of polynitrohexaazaadamantanes （PNHAAs） and the potential candidates of high energy density compounds （HEDCs）. The structural parameters of PNHAAs, such as the the maximum N-NO2 hond length （LBmax）, the least N-N Mulliken population （BN-N）, the least negative charge on the nitro group （QNO2） and OB100, were studied to predict their relative stability or sensitivity （the easiness for initiating a detonation, high sensitivity means low stability）. It was found that the same conclusion was drawn from the four parameters. With the number of nitro groups increasing, the stabilities of these compounds decrease. OB100 failed in identifying the isomers, but the EZpE energy and the dipole moment were considered to give more reliable results for the isomers.展开更多
Chaos theory is used to prove that erratic and chaotic fluctuations can indeed arise in completely deterministic models. Chaos theory reveals structure in aperiodic, dynamic systems. The number of nonlinear business c...Chaos theory is used to prove that erratic and chaotic fluctuations can indeed arise in completely deterministic models. Chaos theory reveals structure in aperiodic, dynamic systems. The number of nonlinear business cycle models use chaos theory to explain complex motion of the economy. Almost three years after the crisis, the G7 countries continue to be challenged with economic volatility. The global economy has slowed. Growth in the United States has weakened. In Europe, economic instability is generated by the financial and economic imbalances. Europe is gripped with financial strains from the sovereign debt crisis in the euro area periphery. How these G7 economies confront their fiscal challenges will profoundly affect their economic stability. The basic aim of this paper is to provide a relatively simple chaotic economic growth model that is capable of generating stable equilibria, cycles, or chaos. This paper looks in more detail at the GDP growth stability issues in each of the G7 countries in the period 1990-2012 （Retrieved from http：//www, imf.org）. A key hypothesis of this work is based on the idea that the coefficient π =[p（s_p-i-n/pb-p_mb_m）] plays a crucial role in explaining local stability of the gross domestic product growth, where, p---the coefficient of labour productivity; p.,--the coefficient of the marginal labour productivity, sp-private saving rate;i--investment rate; b-percent of the gross domestic product which belongs to budget deficit; bm-marginal budget deficit coefficient; n-net capital outflow rate.展开更多
We present here a brief summary of a National Natural Science Foundation Major Project entitled "Theoretical study of the low-lying electronic excited state for molecular aggregates". The project focuses on ...We present here a brief summary of a National Natural Science Foundation Major Project entitled "Theoretical study of the low-lying electronic excited state for molecular aggregates". The project focuses on theoretical investigation of the electronic structures and dynamic processes upon photo-and electric-excitation for molecules and aggregates. We aim to develop reliable methodology to predict the optoelectronic properties of molecular materials related to the electronic excitations and to apply in the experiments. We identify two essential scientific challenges: (i) nature of intramolecular and intermolecular electronic excited states; (ii) theoretical description of the dynamic processes of the coupled motion of electronic excitations and nucleus. We propose the following four subjects of research: (i) linear scaling time-dependent density-functional theory and its application to open shell system; (ii) computational method development of electronic excited state for molecular aggregates; (iii) theoretical investigation of the time evolution of the excited state dynamics; (iv) methods to predict the optoelectronic properties starting from electronic excited state investigation for organic materials and experimental verifications.展开更多
基金This work was supported by the National Natural Science Foundation of China （No.21173158 and No.21373152） and the Ministry of Science and Tech- nology of China （No.2012YQ220113-7）.
文摘The reaction of laser-ablated vanadium, niobium and tantalum atoms with hydrogen sulfide has been investigated using matrix isolation FTIR and theoretical calculations. The metal atoms inserted into the H-S bond of H2S to form the HMSH molecules （M=V, Nb, Ta）, which rearranged to H2MS molecules on annealing for Nb and Ta. The HMSH molecule can also further react with another H2S to form the H2M（SH）2 molecules. These new molecules were identified on the basis of the D2S and H234S isotopic substitutions. DFT （B3LYP and BPW91） theoretical calculations are used to predict energies, geometries, and vibrational frequencies for these novel metal dihydrido complexes and molecules. Reaction mechanism for formation of group V dihydrido complex was investigated by DFT internal reaction coordinate calculations. The dissociation of HVSH gave VS＋H2 on broad band irradiation and reverse reaction happened on annealing. Based on B3LYP calculation releasing hydrogen from HVSH is endothermic only by 13.5 kcal/mol with lower energy barrier of 16.9 kcal/mol.
基金Project(50575143)supported by the National Natural Science Foundation of ChinaProject(20040248005)supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘The bulk metal forming processes were simulated by using a one-step finite element(FE)approach based on deformation theory of plasticity,which enables rapid prediction of final workpiece configurations and stress/strain distributions.This approach was implemented to minimize the approximated plastic potential energy derived from the total plastic work and the equivalent external work in static equilibrium,for incompressibly rigid-plastic materials,by FE calculation based on the extremum work principle.The one-step forward simulations of compression and rolling processes were presented as examples,and the results were compared with those obtained by classical incremental FE simulation to verify the feasibility and validity of the proposed method.
基金Ⅴ. ACKN0WLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.10576016 and No.10576030）.
文摘The density function theory at the B3LYP/6-31G＊ level was employed to study the structures, including the total energies （EZpE）, the geometries, the oxygen balances （OB100）, the dipole moments, of polynitrohexaazaadamantanes （PNHAAs） and the potential candidates of high energy density compounds （HEDCs）. The structural parameters of PNHAAs, such as the the maximum N-NO2 hond length （LBmax）, the least N-N Mulliken population （BN-N）, the least negative charge on the nitro group （QNO2） and OB100, were studied to predict their relative stability or sensitivity （the easiness for initiating a detonation, high sensitivity means low stability）. It was found that the same conclusion was drawn from the four parameters. With the number of nitro groups increasing, the stabilities of these compounds decrease. OB100 failed in identifying the isomers, but the EZpE energy and the dipole moment were considered to give more reliable results for the isomers.
文摘Chaos theory is used to prove that erratic and chaotic fluctuations can indeed arise in completely deterministic models. Chaos theory reveals structure in aperiodic, dynamic systems. The number of nonlinear business cycle models use chaos theory to explain complex motion of the economy. Almost three years after the crisis, the G7 countries continue to be challenged with economic volatility. The global economy has slowed. Growth in the United States has weakened. In Europe, economic instability is generated by the financial and economic imbalances. Europe is gripped with financial strains from the sovereign debt crisis in the euro area periphery. How these G7 economies confront their fiscal challenges will profoundly affect their economic stability. The basic aim of this paper is to provide a relatively simple chaotic economic growth model that is capable of generating stable equilibria, cycles, or chaos. This paper looks in more detail at the GDP growth stability issues in each of the G7 countries in the period 1990-2012 （Retrieved from http：//www, imf.org）. A key hypothesis of this work is based on the idea that the coefficient π =[p（s_p-i-n/pb-p_mb_m）] plays a crucial role in explaining local stability of the gross domestic product growth, where, p---the coefficient of labour productivity; p.,--the coefficient of the marginal labour productivity, sp-private saving rate;i--investment rate; b-percent of the gross domestic product which belongs to budget deficit; bm-marginal budget deficit coefficient; n-net capital outflow rate.
基金the National Natural Science Foundation of China (21290190)
文摘We present here a brief summary of a National Natural Science Foundation Major Project entitled "Theoretical study of the low-lying electronic excited state for molecular aggregates". The project focuses on theoretical investigation of the electronic structures and dynamic processes upon photo-and electric-excitation for molecules and aggregates. We aim to develop reliable methodology to predict the optoelectronic properties of molecular materials related to the electronic excitations and to apply in the experiments. We identify two essential scientific challenges: (i) nature of intramolecular and intermolecular electronic excited states; (ii) theoretical description of the dynamic processes of the coupled motion of electronic excitations and nucleus. We propose the following four subjects of research: (i) linear scaling time-dependent density-functional theory and its application to open shell system; (ii) computational method development of electronic excited state for molecular aggregates; (iii) theoretical investigation of the time evolution of the excited state dynamics; (iv) methods to predict the optoelectronic properties starting from electronic excited state investigation for organic materials and experimental verifications.
