Molecular Reaction Statics Research Articles

Quantum chemical study on the structure and the analytic potential energy function of PS2 (X2A1)

The equilibrium geometry of the ground electronic state of PS2 are calculated using B3LYP, B3P86, CCSD(T), and QCISD(T) methods with 6-311G** and cc-pVTZ basis sets. Compared with the experimental values and other available theoretical results, B3P86/cc-pVTZ method can give best energy calculations for PS2 molecule. Based on the principle of atomic and molecular reaction statics, the possible electronic states and their reasonable dissociation limits of PS2 molecule are determined. Then the contour potential lines of PS2 molecule is first derived in many-body expansion method form. The potential curves correctly reproduce the configurations and the dissociation energy for the PS2 molecule.

Study on the spectroscopic data and vibrational levels of the ground SiH+ molecular ion

The ground electronic state and the reasonable dissociation limit of SiH+ molecular ion have been correctly determined based on group theory and atomic and molecular reaction statics. The energy, equilibrium geometry and harmonic frequency of the ground electronic state of SiH+ molecular ion have been calculated using the method QCISD(T)/cc-pVQZ. The whole potential curves for the ground electronic state is further scanned using the above method, the potential energy functions and relevant spectroscopic constants of this state are then first obtained by least square fitting to the Murrell-Sorbie function (n=9) and the modified Murrell-Sorbie+c6 function, respectively. The present results showed that the calculated results based on the Murrell-Sorbie function (n=9) are in better agreement with the experimental values, with the relative errors between spectroscopic constants and the experimental values being 0.13%, 3.07%, 0.38%, 5.25% and 0.52% respectively. With the potential obtained at the QCISD(T)/cc-pVQZ level of theory, the total of 27 vibrational states are predicted when J=0 by numerically solving the radial Schrodinger equation of nuclear motion. The complete vibrational levels, inertial rotation and six centrifugal distortion constants are obtained for the ground electronic state of SiH+ molecular ion for the first time. Calculation results in the present work may provide theoretical supports for the further study of SiH+ molecular ion.

Theoretical study of the structure and analytic potential energy function for the ground state of the PO2 molecule

In this paper, the energy, equilibrium geometry, and harmonic frequency of the ground electronic state of PO2 are computed using the B3LYP, B3P86, CCSD(T), and QCISD(T) methods in conjunction with the 6–311++G(3df, 3pd) and cc-pVTZ basis sets. A comparison between the computational results and the experimental values indicates that the B3P86/6-311++G(3df, 3pd) method can give better energy calculation results for the PO2 molecule. It is shown that the ground state of the PO2 molecule has C2ν symmetry and its ground electronic state is X2A1. The equilibrium parameters of the structure are RP−O = 0.1465 nm, ∠OPO = 134.96°, and the dissociation energy is Ed = 19.218 eV. The bent vibrational frequency ν1 = 386 cm−1, symmetric stretching frequency ν2 = 1095 cm−1, and asymmetric stretching frequency ν3 = 1333 cm−1 are obtained. On the basis of atomic and molecular reaction statics, a reasonable dissociation limit for the ground state of the PO2 molecule is determined. Then the analytic potential energy function of the PO2 molecule is derived using many-body expansion theory. The potential curves correctly reproduce the configurations and the dissociation energy for the PO2 molecule.

Theoretical Study on the Low-Lying Electronic States of He2, He+2, and He++2

The equilibrium geometries, potential energy curves, spectroscopic dissociation energies of the ground and low-lying electronic states of He2, He+2 and He++2 are calculated using symmetry adapted cluster/symmetry adapted cluster-configuration interaction (SAC/SAC-CI) method with the basis sets CC-PV5Z. The corresponding dissociation limits for all states are derived based on atomic and molecular reaction statics. The analytical potential energy functions of these states are fitted with Murrell—Sorbie potential energy function from our calculation results. The spectroscopic constants Be, αe, ωe, and ωeχe of these states are calculated through the relationship between spectroscopic data and analytical energy function, which are in well agreement with the experimental data. In addition, the origin of the energy barrier in the ground state X1Σg+ of He2++ energy curve are explained using the avoided crossing rules of valence bond model.

The analytical potential energy function of flue gas SO2(X1A1)

The equilibrium structure of flue gas SO2 is optimized using the density functional theory (DFT)/B3P86 method and CC-PV5Z basis. The result shows that it has a bent (C2V, X1A1) ground state structure with an angle of 119.1184°. The vibronic frequencies and the force constants are also calculated. Based on the principles of atomic and molecular reaction statics (AMRS), the possible electronic states and reasonable dissociation limits for the ground state of SO2 molecule are determined. The potential functions of SO and O2 are fitted by the modified Murrell—Sorbie+c6 (M-S+c6) potential function and the fitted parameters, the force constants and the spectroscopic constants are obtained, which are all close to the experimental values. The analytic potential energy function of the SO2 (X1A1) molecule is derived using the many-body expansion theory. The contour lines are constructed, which show the static properties of SO2 (X1A1), such as the equilibrium structure, the lowest energies, the most possible reaction channel, etc.

Structures and potential energy functions of the ground states of YH,YD,YT molecules

Using the density functional theory(B3LYP) method, the 6-311++G(3df,2pd), AUG-cc-PVTZ, AUG-cc-PVQZ basis sets for H and effective core potentials for Y, the energies, equilibrium structure and harmonic frequency of the ground states of YH(D,T) molecules are calculated. Based on the theory of atomic and molecular reaction statics, the reasonable dissociation limits of the ground states of YH(D,T) molecules are derived. By comparing the calculation results with the existing experimental and theoretical values, we find that the mixed basis sets LANL2TZ/AUG-cc-PVQZ are most suited for the calculation of the molecules. Consequently, the potential energy surfaces of the ground states of YH(D,T) molecules are scanned at the B3LYP/LANL2TZ/AUG-cc-PVQZ level of theory. The potential energy curves of the ground states of YH(D,T) molecules are obtained by the least square fitting to the Murrell-Sorbie potential energy function. The spectroscopic constants (Be, e, e, ee, De) and force constants ((f2, f3, f4)are calculated and compared with experimental results, indicating that the calculation results are in good agreement with the experimental data.

The structure and the potential energy function of AlSO(CS,X2A″)

By using the B3P86/aug-cc-pvtz method, the accurate equilibrium geometry of the AlSO (CS,X2A″) molecule has been calculated and compared with available theoretical values. The obtained results show that the AlSO molecule has a most stable structure with bond lengths of ROAl = 0.1864 nm, ROS = 0.1623 nm, RAlS = 0.2450 nm, together with a dissociation energy of 13.88 eV. The possible electronic states and their reasonable dissociation limits for the ground state of the AlSO molecule were determined based on the principle of atomic and molecular reaction statics. The analytic potential energy function of the AlSO molecule was derived by the many-body expansion theory and the contour lines were constructed for the first time, which show the internal information of the AlSO molecule, including the equilibrium structure and stable point. The analysis demonstrates that the obtained potential energy function of AlSO is reasonable and successful and the present investigations provide important insights for further study on molecular reaction dynamics.

Ab Initio Calculation of Interatomic Potentials in Ga-Stabilized δ-Pu Alloys

Abstract To perform molecular dynamics (MD) simulation of self-radiation effects in Ga-stabilized δ-Pu alloys, spectral representation 7Fg(9Fg), 2Pu(4Pu) and 1Sg(3Sg) of Pu, Ga and He atoms are resolved into the direct sum of Pu2(D∞h), PuGa(C∞v), Ga2 (D∞h), PuHe (C∞v), GaHe (C∞v), He2 (D∞h) according to atomic and molecular reaction statics, respectively. All possible electronic states can be derived by the direct product and reduction operation. The Pu-Pu, Pu-Ga, Pu-He, Ga-Ga, Ga-He and He-He potential data have been implemented ab initio calculation using relativistic alloy effective core potential (RECP) for Pu atom, 6-311G* all electron basis sets for Ga atom and He atom with Becke-3 hybrid functional (B3LYP). Interatomic potentials and electron states of the corresponding molecular have been obtained.

The structure and analytical potential energy function of the ground state of HNO molecule

The ground electronic state and the reasonable dissociation limit of HNO molecule are determined based on the group theory and the atomic and molecular reaction statics. The energy, the equilibrium geometry and the harmonic frequency of the ground electronic state of HNO are calculated using the density functional theory B3LYP method in combination with the 6-311G ** basis set. The computational results show that the ground state of HNO molecule has CS symmetry, its ground electronic state is X1A', and the equilibrium parameters of the structure are RHN=0.1065nm, RNO=0.1200 nm,HNO=108.60, dissociation energy De=15.379 eV, bending vibrational frequency 1=1575.6351 cm-1, symmetric stretch frequency 2=1673.2890 cm-1, and asymmetric stretch frequency 3=2837.7856 cm-1. Then the analytic potential energy function of HNO molecule is derived by the many-body expansion theory. The potential curves correctly describe the configurations and the dissociation energy for the HNO molecule.

Potentional Energy Functions and the First Vertical Ionization Potential of XO<sup><em>n</em>+</sup> (X=Ru, Rh, Pd|<em>n</em>=0, 1)

Based on the atomic and molecular reaction statics,the ground electronic states of XOn+(X=Ru,Rh,Pd;n=0,1) and their corresponding dissociation limits were systematically examined. Using the density functional B3P86 method in conjunction with the LANL2DZ basis set for X atoms and aug-cc-pVTZ basis set for O atom,we investigated molecular equilibrium geometries and dissociation energies for these systems. Analytical potential energy functions of XOn+(X=Ru,Rh,Pd;n=0,1) were determined using the Murrell-Sorbie function. Spectroscopic data for XOn+(X=Ru,Rh,Pd;n=0,1) and the first vertical ionization potentials of the neutral XO(X=Ru,Rh,Pd) molecules were calculated as well.

Structure and analytic potential energy function for the ground state of SiF2 molecule

The density function （B3P86） method has been used to optimize the possible ground-state structure of SiF2 molecule. The results show that the ground state of SiF2 molecule has C2v symmetry and its electronic ground state is X1A1. The equilibrium parameters of the structure are RSi—F=0.1061 nm and De=13.8 eV. On the base of atomic and molecular reaction statics, the reasonable dissociation limit for the ground state of SiF2 molecule is determined. Then the analytic potential energy function of SiF2 molecule is derived by many-body expansion theory. The potential curves describe correctly the configurations and the dissociation energy for the SiF2 molecule.

Ground state for CH2 and symmetry for methane decomposition

Using the different level of methods B3P86, BLYP, B3PW91, HF, QCISD, CASSCF (4,4) and MP2 with the various basis functions 6-311G**, D95, cc-pVTZ and DGDZVP, the calculations of this paper confirm that the ground state is X̃3B1 with C2v group for CH2. Furthermore, the three kinds of theoretical methods, i.e. B3P86, CCSD(T, MP4) and G2 with the same basis set cc-pVTZ only are used to recalculate the zero-point energy revision which are modified by scaling factor 0.989 for the high level based on the virial theorem, and also with the correction for basis set superposition error. These results are also contrary to X̃3Σ−g for the ground state of CH2 in reference. Based on the atomic and molecular reaction statics, this paper proves that the decomposition type (1) i.e. CH4 → CH2+H2, is forbidden and the decomposition type (2) i.e. CH4 → CH3+H is allowed for CH4. This is similar to the decomposition of SiH4.

The structure and potential energy function of SiOH and HSiO

By using B3P86/6-311++G** method, the equilibrium geometry of SiOH/HSiO (CS，X2A′)molecule has been calculated .The possible electronic state and the reasonable dissociation limit for the ground state of SiOH molecule is determined based on atomic and molecular reaction statics. The analytic potential energy function of SiOH molecule was derived by many-body expansion theory.

The structure and potential energy function of AlOH(CS，X1A′)

By using MP4/6-311G(3df,3pd) method, the equilibrium geometry of AlOH molecule has been calculated .The possible electronic state and the reasonable dissociation limit for the ground state of AlOH (CS，X1A′) molecule is determined based on atomic and molecular reaction statics. The analytic potential energy function of AlOH molecule was derived by many-body expansion theory.

The atomic and molecular reaction statics

This work presents a new science called atomic and molecular reaction statics (AMRS). There are four parts for AMRS, i.e. the group theoretical derivation of molecular electronic states, the principle of microscopic reversibility, the principle of microscopic transitivity and the optimum energy process rule. AMRS has been developed for about twenty years.

The molecular structure and analytical potential energy function of HCO ( X 2 A' )

In this paper the equilibrium structure of HCO has been optimized by using density functional theory (DFT)/ B3P86 method and CC-PVTZ basis. It has a bent (Cs, X2A') ground state structure with an angle of 124.4095 °. The vibronic frequencies and force constants have also been calculated. Based on the principles of atomic and molecular reaction statics, the possible electronic states and reasonable dissociation limits for the ground state of HCO molecule have been determined. The analytic potential energy function of HCO (X2 A') molecule has been derived by using the many-body expansion theory. The contour lines are constructed, which show the static properties of HCO (X2A'), such as the equilibrium structure, the lowest energies, etc. The potential energy surface of HCO (X2A') is reasonable and very satisfactory.

The structure and potential energy function of LiO2(C2V，X2A2) molecule

By using QCISD(T)/aug-cc-pvtz method, the equilibrium geometry of LiO2 molecule has been calculated. The possible electronic state and the reasonable dissociation limit of the ground state of LiO2 molecule is determined based on atomic and molecular reaction statics. The analytic potential energy function of LiO2(C2V，X2A2) molecule was derived by many-body expansion theory.

Structure and analytic potential energy function for the ground state of SiO2 molecule

The equilibrium geometry of SiO and SiO2 molecule has been calculated on the computational levels of density functional theory (DFT). The possible electronic state and reasonable dissociation limit for the ground state of SiO and SiO2 X1A1 molecule are determined based on atomic and molecular reaction statics. And Murrell-Sorbie analytic potential energy function of SiO molecule has been derived through the least-square fitting to ab initio data. Similarly, the harmonic frequency has been calculated, and the analytic potential energy function of SiO2 molecule has been derived using many-body expansion theory.

Structure and analytical potential energy function for the ground state of the BCx(x=0, –1)

In this paper, the electronic states of the ground states and dissociation limits of BC and BC− are correctly determined based on group theory and atomic and molecular reaction statics. The equilibrium geometries, harmonic frequencies and dissociation energies of the ground state of BC and BC− are calculated by using density function theory and quadratic CI method including single and double substitutions. The analytical potential energy functions of these states have been fitted with Murrell–Sorbie potential energy function from our ab initio calculation results. The spectroscopic data (αe, ωe and ωeχe) of each state is calculated via the relation between analytical potential energy function and spectroscopic data. All the calculations are in good agreement with the experimental data.

Potentional energy function of CrHn(n=0,+1,+2)

Based on the atomic and molecular reaction statics, the ground electronic states of CrH(X6Σ+), CrH+(5Σ+), CrH2+ (6Σ+) and their dissociation limits have been derived. Using density functional method (B3PW91), 6-311++G** basis sets for H and split valence polarization basis sets for Cr, the molecular equilibrium geometry and dissociation energies for CrH+(5Σ+) and CrH2+ (6Σ+) have been calculated. The analytical potential energy functions for CrH(X6Σ+), CrH+(5Σ+) and CrH2+ (6Σ+) are determined. The force fields and spectroscopic parameters have been worked out from these analytical potential energy functions. For the ground state of CrH+, the calculated results of Re, f2, f3, f4, Be, αe, ωe and ωeχe are 0.16200 nm, 1.52574 aJ/nm2, -7.81171 aJ/nm3, 28.61613 aJ/nm4, 6.71181, 0.28792, 1624.6297 and 53.55394 cm-1, respectively; and for the ground state of CrH2+, the corresponding parameters are 0.24005 nm, 0.42946 aJ/nm2, -0.97766 aJ/nm3, 2.40438 aJ/nm4, 2.9562, 0.050184, 858.059 and 6.46813 cm-1, respectively. The theoretical results show minimum points in the potential energy curves of CrH+(5Σ+) and CrH(X6Σ+), so we conclude that CrH(X6Σ+) and CrH+(5Σ+) are stable.But there are no minimum points in the potential energy curves of CrH2+ (6Σ+), so CrH2+ (6Σ+) is not stable.