Xie An-Dong

The geometry structures and electronic properties of LimBn (m + n = 12) clusters

The geometric structures, electronic properties, total and binding energies, harmonic frequencies, the highest occupied molecular orbital to the lowest unoccupied molecular orbital energy gaps, and the vertical ionization potential energies of small LimBn (m+n = 12) clusters were investigated by the density functional theory B3LYP with a 6-311+G (2d, 2p) basis set. All the calculations were performed using the Gaussian09 program. For the study of the LimBn clusters, the global minimum of the B12 cluster was chosen as the starting point and the boron atoms were gradually replaced by Li atoms. The results showed that as the number of Li atoms increased, the stability of the LimBn cluster decreased and the physical and chemical properties became more active. In addition, on average there was a large charge transfer from the Li atoms to the B atoms.

Molecular properties and potential energy function model of BH under external electric field

Using the density functional B3P86/cc-PV5Z method, the geometric structure of BH molecule under different external electric fields is optimized, and the bond lengths, dipole moments, vibration frequencies, and other physical properties parameters are obtained. On the basis of setting appropriate parameters, scanning single point energies are obtained by the same method and the potential energy curves under different external fields are also obtained. These results show that the physical property parameters and potential energy curves may change with external electric field, especially in the case of reverse direction electric field. The potential energy function without external electric field is fitted by Morse potential, and the fitting parameters are obtained which are in good agreement with experimental values. In order to obtain the critical dissociation electric parameter, the dipole approximation is adopted to construct a potential model fitting the corresponding potential energy curve of the external electric field. It is found that the fitted critical dissociation electric parameter is consistent with numerical calculation, so that the constructed model is reliable and accurate. These results will provide important theoretical and experimental reference for further studying the molecular spectrum, dynamics, and molecular cooling with Stark effect.Using the density functional B3P86/cc-PV5Z method, the geometric structure of BH molecule under different external electric fields is optimized, and the bond lengths, dipole moments, vibration frequencies, and other physical properties parameters are obtained. On the basis of setting appropriate parameters, scanning single point energies are obtained by the same method and the potential energy curves under different external fields are also obtained. These results show that the physical property parameters and potential energy curves may change with external electric field, especially in the case of reverse direction electric field. The potential energy function without external electric field is fitted by Morse potential, and the fitting parameters are obtained which are in good agreement with experimental values. In order to obtain the critical dissociation electric parameter, the dipole approximation is adopted to construct a potential model fitting the corresponding potential energy curve of the external electric field. It is found that the fitted critical dissociation electric parameter is consistent with numerical calculation, so that the constructed model is reliable and accurate. These results will provide important theoretical and experimental reference for further studying the molecular spectrum, dynamics, and molecular cooling with Stark effect.

Na decorated B6 cluster and its hydrogen storage properties

The structures and hydrogen storage properties of sodium atoms decorated B6 clusters are investigated by the B3LYP method with a 6–311+G (d, p) basis set. For NamB6 (m = 1–3) clusters, Na atoms are always inclined to separate far enough from each other and not cluster together on a B6 cluster surface so that each Na atom has sufficient space to bind hydrogen molecules. The hydrogen storage gravimetric density of a two Na atoms decorated B6 cluster is 17.91 wt% with an adsorption energy per H2 molecule (AAE/H2) of 0.6851 kcalmol−1. The appropriate AAE/H2 and preferable gravimetric density of the two Na atoms decorated B6 cluster complex indicate that it is feasible for hydrogen storage application in ambient conditions.

Study on high-temperature spectra of asymptotic asymmetric-top radical SiO2

Total internal partition sums are calculated in the product approximation at temperatures up to 6000 K for the asymptotic asymmetric-top SiO2 molecule. The rotational partition function and the vibrational partition function are calculated with the rigid-top model and in the harmonic oscillator approximation, respectively. Our values of the total internal partition sums are consistent with the calculated value in the Gaussian program within −0.137% at 296 K. Using the calculated partition functions and the rotationless transition dipole moment squared as a constant, we calculate the line intensities of 001–000 band of SiO2 at normal, medium and high temperatures. Simulated spectra of the 001–000 band of the asymptotic asymmetric-top SiO2 molecule at 2000, 5000 and 6000 K are also obtained.

Spin polarization effect for Ta2 molecule

Density functional theory (DFT) (B3p86) has been used to optimize the structure of the molecule Ta2. The result shows that the ground state of molecule Ta2 is a 7-multiple state and its electronic configuration is 7Σu+, which shows the spin polarization effect for molecule Ta2 of transition metal elements for the first time. Meanwhile, spin pollution has not been found because the wavefunction of the ground state does not mix with those of higher states. So, the fact that the ground state of molecule Ta2 is a 7-multiple state indicates a spin polarization effect of molecule Ta2 of the transition metal elements, i.e. there exist 6 parallel spin electrons and the non-conjugated electrons are greatest in number. These electrons occupy different space orbitals so that the energy of molecule Ta2 is minimized. It can be concluded that the effect of parallel spin of the Ta2 molecule is larger than the effect of the conjugated molecule, which is obviously related to the effect of d-electron delocalization. In addition, the Murrell–Sorbie potential functions with parameters for the ground state 7Σu+ and other states of the Ta2 molecule are derived. The dissociation energy De, equilibrium bond length Re and vibration frequency ωe for the ground state of Ta2 molecule are 4.5513eV, 0.2433 nm and 173.06 cm−1, respectively. Its force constants f2, f3 and f4 are 1.5965×102aJ.nm−2, –6.4722×103aJ.nm−3 and 29.4851×104aJ.nm−4, respectively. Other spectroscopic data ωe χe, Be and αe for the ground state of Ta2 are 0.2078 cm−1, 0.0315 cm−1 and 0.7858×10−4 cm−1, respectively.

Spin polarization effect for Os2 molecule

Density functional Theory (DFT) (B3p86) of Gaussian03 has been used to optimize the structure of Os2 molecule. The result shows that the ground state for Os2 molecule is 9-multiple state and its electronic configuration is 9Σg+, which shows spin polarization effect of Os2 molecule of transition metal elements for the first time. Meanwhile, we have not found any spin pollution because the wavefunction of the ground state does not mingle with wavefunctions with higher energy states. So, the fact that the ground state for Os2 molecule is a 9-multiple state is indicative of spin polarization effect of Os2 molecule of transition metal elements. That is, there exist 8 parallel spin electrons. The non-conjugated electron is greatest in number. These electrons occupy different spacious tracks, so that the energy of Os2 molecule is minimized. It can be concluded that the effect of parallel spin of Os2 molecule is larger than the effect of the conjugated molecule, which is obviously related to the effect of electron d delocalization. In addition, the Murrell–Sorbie potential functions with the parameters for the ground state 9Σg+ and other states of Os2 molecule are derived. Dissociation energy De for the ground state of Os2 molecule is 3.3971eV, equilibrium bond length Re is 0.2403nm, vibration frequency ωe is 235.32cm−1. Its force constants f2, f3 and f4 are 3.1032×102aJ.nm−2, −14.3425×103aJ.nm−3 and 50.5792×104aJ.nm−4 respectively. The other spectroscopic data for the ground state of Os2 molecule ωeχe, Be and αe are 0.4277cm−1, 0.0307cm−1 and 0.6491× 10−4cm−1 respectively.

Analytical Potential Energy Functions for the Electronic States X 1 Σ + , A 1 Π and B 1 Σ + of BH Molecule

The equilibrium geometries of three electronic states X 2 Σ + ， A 2 Π and B 2 Σ + of MgH molecule have been calculated using the SAC-CI and QCISD (T) methods with the basis sets cc-pVQZ，aug-cc-pVTZ，6-311++G and 6-311++G(3df，2pd). Comparing the above mentioned four basis sets，the conclusion is obtained that the basis set 6-311++G (3df，2pd) is the most suitable for the energy calculation of MgH molecule. The whole potential curves for three electronic states are further scanned using QCISD (T)/6-311++G (3df，2pd) method for the ground state and SAC-CI/6-311++G (3df，2pd) method for the excited states. The potential energy functions and relevant spectrum constants ω e ， ω e x e ， B e ， α e of these states are obtained by fitting to the Murrell-Sorbie function and the modified Murrell-Sorbie+ C 6 function，respectively. The results showed that the spectral constants derived from the modified Murrell-Sorbie+ C 6 function are in very good agreement with the experimental data，and the modified Murrell-Sorbie+ C 6 function can correctly describe the potential energy function of the ground state and the first degenerate state of MgH molecule.The equilibrium geometries of three electronic states X 2 Σ + ， A 2 Π and B 2 Σ + of MgH molecule have been calculated using the SAC-CI and QCISD (T) methods with the basis sets cc-pVQZ，aug-cc-pVTZ，6-311++G and 6-311++G(3df，2pd). Comparing the above mentioned four basis sets，the conclusion is obtained that the basis set 6-311++G (3df，2pd) is the most suitable for the energy calculation of MgH molecule. The whole potential curves for three electronic states are further scanned using QCISD (T)/6-311++G (3df，2pd) method for the ground state and SAC-CI/6-311++G (3df，2pd) method for the excited states. The potential energy functions and relevant spectrum constants ω e ， ω e x e ， B e ， α e of these states are obtained by fitting to the Murrell-Sorbie function and the modified Murrell-Sorbie+ C 6 function，respectively. The results showed that the spectral constants derived from the modified Murrell-Sorbie+ C 6 function are in very good agreement with the experimental data，and the modified Murrell-Sorbie+ C 6 function can correctly describe the potential energy function of the ground state and the first degenerate state of MgH molecule.