Sun Jin-Feng

Analytical Potential Energy Function, Spectroscopic Constants and Vibrational Levels for A1Σ+u State of Dimer 7Li2

The symmetry-adapted-cluster configuration-interaction method is used to investigate the spectroscopic properties of 7Li2(A1Σ+u) over the internuclear distance ranging from 2.4a0 to 37a0. The complete potential energy curves are calculated at numbers of basis sets. All the ab initio calculated points are fitted to the analytic Murrell–Sorbie function and then employed to compute the spectroscopic constants. By comparison, the spectroscopic constants reproduced by the potential attained at D95(3df,3pd) are found to be very close to the experiments, and the values (Te, De, Re, ωe, ωeχe, αe and Be) are of 1.732 93 eV, 1.161 36 eV, 0.313 27 nm, 251.95 cm−1, 1.623 cm−1, 0.005 35 cm−1, and 0.490 cm−1, respectively. With the potential obtained at D95(3df,3pd), the totally 75 vibrational states are found when J = 0. The vibrational levels, the classical turning points and the inertial rotation constants of the first 68 vibrational states are calculated for the first time and compared with the available measurements. Good agreement is obtained. The centrifugal distortion constants of the first 32 vibrational states are also reported for the first time. The reasonable dissociation limit for 7Li2(A1Σ+u) is deduced using the calculated results at present.

Accurate Analytic Potential Energy Function and Spectroscopic Study for G1Πg State of Dimer 7Li2

The reasonable dissociation limit for the G1Πg state of dimer 7Li2 is determined. The equilibrium internuclear distance, dissociation energy, harmonic frequency, vibrational zero energy, and adiabatic excitation energy are calculated using a symmetry-adapted-cluster configuration-interaction method in complete active space in Gaussian03 program package at such numerous basis sets as 6-311++G, 6-311++G(2df,2pd), 6-311++G(2df,p), cc-PVTZ, 6-311++G(3df,3pd), CEP-121G, 6-311++G(2df,pd), 6-311++G(d,p),6-311G(3df,3pd), D95(3df,3pd), 6-311++G(3df,2p), 6-311++G(2df), 6-311++G(df,pd) D95V++, and DGDZVP. The complete potential energy curves are obtained at these sets over a wide internuclear distance range and have least squares fitted to Murrell–Sorbie function. The conclusion shows that the basis set 6-311++G(2df,p) is a most suitable one for the G1Πg state. At this basis set, the calculated spectroscopic constants Te, De, E0, Re, ωe, ωeχe, αe, and Be are of 3.9523 eV, 0.813 06 eV, 113.56 cm−1, 0.320 15 nm, 227.96 cm−1, 1.6928 cm−1, 0.004 436 cm−1, and 0.4689 cm−1, respectively, which are in good agreement with measurements whenever available. The total 50 vibrational levels and corresponding inertial rotation constants are for the first time calculated and compared with available RKR data. And good agreement with measurements is obtained.

Effects of Raw Material Content on Efficiency of TiN Synthesized by Reactive Ball Milling Ti and Urea

Ti and urea mixed according to the molar ratios of 2:1, 3:1 and 4:1 are milled under the same condition. The structures of the as-synthesized powders are analyzed by an x-ray diffractometer (XRD). The decomposed temperature of the urea and the products decomposed are characterized by differential scanning calorimetry (DSC) and thermogravimetry analysis-Fourier transform infrared (TG-FTIR) spectrometry. The results show that the reaction progress is a diffusion reaction. The efficiency of TiN synthesized by reactive ball milling can be increased by increasing the content of Ti. The reactive ball milling time decreases from more than 90 h to 40 h corresponding to the content ratio between Ti and urea increasing from 2:1 to 4:1. Ammonia gas (NH3) and cyanic acid (HNCO), the decomposed products of urea, react with the refined Ti to form TiN. The grain refinement of Ti has a significant effect on the efficiency of reactive ball milling.

Ab initio calculations on the spectroscopic constants, vibrational levels and classical turning points for the 2 1 ∏ u state of dimer 7 Li 2

The accurate dissociation energy and harmonic frequency for the highly excited 21Πu state of dimer 7Li2 have been calculated using a symmetry-adapted-cluster configuration-interaction method in complete active space. The calculated results are in excellent agreement with experimental measurements. The potential energy curves at numerous basis sets for this state are obtained over a wide internuclear separation range from about 2.4a0 to 37.0a0. And the conclusion is gained that the basis set 6-311++G(d,p) is a most suitable one. The calculated spectroscopic constants De, Re, ωe, ωeχe, αe and Be at 6-311++G(d,p) are 0.9670 eV, 0.3125 nm, 238.6 cm−1, 1.3705 cm−1, 0.0039 cm−1 and 0.4921 cm−1, respectively. The vibrational levels are calculated by solving the radial Schrodinger equation of nuclear motion. A total of 53 vibrational levels are found and reported for the first time. The classical turning points have been computed. Comparing with the measurements, in which only the first nine vibrational levels have been obtained so far, the present calculations are very encouraging. A careful comparison of the present results of the parameters De and ωe with those obtained from previous theories clearly shows that the present calculations are much closer to the measurements than previous theoretical results, thus representing an improvement on the accuracy of the ab initio calculations of the potentials for this state.

A Correlation Potential Method for Electron Scattering Total Cross Section Calculations on Several Diatomic and Polyatomic Molecules over Energy Range 10~5000 eV

A complex optical model potential correlated by the concept of bonded atom, which considers the overlapping effect of electron clouds between two atoms in a molecule, is firstly employed to calculate the total cross sections for electron scattering on several molecules (NH3, H2O, CH4, CO, N2, O2, and C2H4) over the energy range 10~5000 eV using the additivity rule model at Hartree–Fock level. The difference between the bonded atom and the free one in states is that the overlapping effect of electron clouds of bonded atoms in a molecule is considered. The quantitative total cross sections are compared with the experimental data and with the other calculations wherever available and good agreement is obtained over the energy range 10~5000 eV. It is shown that the correlated calculations are much closer to the available experimental data than the uncorrelated ones at lower energies, especially below 500 eV. Therefore, considering the overlapping effect of electron clouds in the complex optical model potential could be helpful for the better accuracy of the total cross section calculations of electron scattering from molecules.

Spiral and antispiral waves in reaction-diffusion systems

Spiral waves are ubiquitous phenomena in nonlinear chemical, physical, and biological systems. But antispiral waves are infrequent to date. The transition between spiral and antispiral waves has been rarely explored. We have analyzed the extended Brusselator model and the extended Oregonator model by linear stability analysis. We have demonstrated that it is possible and plausible to realize the transition between them by control of diffusion coefficient of inactivator from theoretical analysis and numerical simulations.

MRCI study of spectroscopic and molecular properties of X1Σ+g and A1Πu electronic states of the C2 radical

The potential energy curves (PECs) of X1Σ+g and A1Πu electronic states of the C2 radical have been studied using the full valence complete active space self-consistent field (CASSCF) method followed by the highly accurate valence internally contracted multireference configuration interaction (MRCI) approach in conjunction with the aug-cc-pV6Z basis set for internuclear separations from 0.08 nm to 1.66 nm. With these PECs of the C2 radical, the spectroscopic parameters of three isotopologues (12C2, 12C13C and 13C2) have been determined. Compared in detail with previous studies reported in the literature, excellent agreement has been found. The complete vibrational levels G(υ), inertial rotation constants Bυ and centrifugal distortion constants Dυ for the 12C2, 12C13C and 13C2 isotopologues have been calculated for the first time for the X1Σ+g and A1Πu electronic states when the rotational quantum number J equals zero. The results are in excellent agreement with previous experimental data in the literature, which shows that the presented molecular constants in this paper are reliable and accurate.The potential energy curves (PECs) of X1Σ+g and A1Πu electronic states of the C2 radical have been studied using the full valence complete active space self-consistent field (CASSCF) method followed by the highly accurate valence internally contracted multireference configuration interaction (MRCI) approach in conjunction with the aug-cc-pV6Z basis set for internuclear separations from 0.08 nm to 1.66 nm. With these PECs of the C2 radical, the spectroscopic parameters of three isotopologues (12C2, 12C13C and 13C2) have been determined. Compared in detail with previous studies reported in the literature, excellent agreement has been found. The complete vibrational levels G(υ), inertial rotation constants Bυ and centrifugal distortion constants Dυ for the 12C2, 12C13C and 13C2 isotopologues have been calculated for the first time for the X1Σ+g and A1Πu electronic states when the rotational quantum number J equals zero. The results are in excellent agreement with previous experimental data in the literature, which shows that the presented molecular constants in this paper are reliable and accurate.

Elastic collisions between Si and D atoms at low temperatures and accurate analytic potential energy function and molecular constants of the SiD(X2?) radical

Interaction potential of the OD（ X 2 Π ） radical is constructed by employing the CCSD（T） theory in combination with the correlationconsistent quintuple basis set, augccpV5Z, in the valence range. Using the potential, the spectroscopic parameters are accurately determined. The present D 0 , D e , R e , ω e , ω e χ e and B e values are of 44574, 46225 eV, 009702 nm, 2724923, 453534 and 100096 cm -1 , respectively, which are in excellent agreement with the recent measurements wherever available. A total of 23 vibrational states have been found when J = 0 by solving the radial Schrdinger equation of nuclear motion. The complete vibrational levels, classical turning points, initial rotation and centrifugal distortion constants when J = 0 are reported for the first time, which are in good agreement with the available experimental results. The total and various partialwave cross sections are calculated for the elastic collisions of O and D atoms in their ground states at low and ultralow temperatures when the two atoms approach each other along the OD（ X 2 Π ） potential energy curve. The impact energy range covers a vange from 10×10 -11 to 10 ×10 -3 a.u.. One shape resonance has been found in the total elastic cross sections. Contribution to the total elastic cross sections by each partial wave is investigated carefully. The results show that the shape of the total elastic cross sections is mainly dominated by the s partial wave. The shape resonances coming from the higher partial waves are covered up by the strong s partial wave cross sections.

Ab initio calculation on accurate analytic potential energy functions and harmonic frequencies of c3∑g+ and B1∏u states of dimer 7Li2

The comparison between single-point energy scanning (SPES) and geometry optimization (OPT) in determining the equilibrium geometries of c3∑g+ and B1∏u states of dimer 7Li2 is made at numerous basis sets by using a symmetry-adapted-cluster configuration-interaction (SAC-CI) method in the Gaussian 03 program package. In this paper the difference of the equilibrium geometries obtained by SPES and by OPT is reported. The results obtained by SPES are found to be more reasonable than those obtained by OPT in full active space at the present SAC-CI level of theory. And the conclusion is attained that the cc-PVTZ is a most suitable basis set for these states. The calculated dissociation energies and equilibrium geometries are 0.8818 eV and 0.3090 nm for c3∑g+ state, and 0.3668 eV and 0.2932 nm for B1∏u state respectively. The potential energy curves are calculated over a wide internuclear distance range from about 2.5a0 to 37a0 and have a least-squares fit into the Murrell-Sorbie function. According to the calculated analytic potential energy functions, the harmonic frequencies (ωe) and other spectroscopic data (ωeχe, Be and αe) are calculated. Comparison of the theoretical determinations at present work with the experiments and other theories clearly shows that the present work is the most complete effort and thus represents an improvement over previous theoretical results.

A Modified Potential Method for Electrons Scattering Total Cross Section Calculations on Several Molecules at 30∼5000 eV: CF4, CCl4, CFCl3, CF2Cl2, and CF3Cl

A complex optical model potential modified by the concept of bonded atom, which takes into consideration the overlapping effect of electron clouds between two atoms in a molecule, is employed to calculate the total cross sections (TCSs) for electrons scattering from several molecules (CF4, CCl4, CFCl3, CF2Cl2, and CF3Cl) over an incident energy range 30~5000 eV using the additivity rule model at Hartree–Fock level. The quantitative TCSs are compared with those obtained by experiments and other theories wherever available, and good agreement is obtained above 100 eV. It is shown that the modified potential can successfully calculate the TCSs of electron-molecule scattering over a wide energy range, especially at lower energies.