GaN和GaN2分子基态的结构和解析势能函数

本文利用密度泛函方法,优化了CaN2基态(X2B2)的几何平衡结构,其对称性属于C2v,它的键角、平衡核间距和离解能分别为26.428°,0.2526 nm和9.574 eV.基于量子化学计算得出GaN和GaN2基电子态及其离解极限之后,利用计算数据和最小二乘法得到了GaN的M-S解析势能函数,并计算出各态的谐振频率、力常数和光谱数据.利用多体项展式理论首次得到了GaN2基态的解析势能函数,它准确表达了GaN2的平衡几何结构,在此基础上讨论了Ga N2和N GaN反应系统的反应动力学.     

用CCSD(T)方法计算基态SH和SD的光谱常数(英文)

利用CCSD(T)方法和系列相关一致基cc-pVXZ及aug-cc-pVXZ(X=D,T,Q,5)对SH和SD分子的基态平衡几何,谐振频率和离解能进行了优化计算.利用优选出的CCSD(T)/aug-cc-pV5Z方法对SH和SD的基态进行单点能计算,并将计算结果拟合成了Murrell-Sorbie函数.利用得到的解析势能函数,计算了SH和SD的其余3个光谱常数(ω_ex_e,α_e和B_c),结果表明:除SD的ω_ex_e值外,其余结果均与实验值符合得相当好,但计算得出的ω_ex_e值与推导出的值25.134 cm~(-1)符合得很好.     

OH分子基态(X~2Π)的结构与势能函数

采用密度泛函理论的B3LYP方法和二次组态相互作用(QCISD(T))方法优化计算了OH分子基态(X2Π)的平衡结构、振动频率和离解能.根据原子分子反应静力学原理,导出了OH分子基态(X2Π)的合理离解极限,采用最小二乘法拟合Murrell-Sorbie函数得到了相应的势能函数和与该基态相对应的光谱常数(Be,αe,ωe和ωeχe),计算结果与实验数据符合得相当好.     

OH分子基态(X2Ⅱ)的结构与势能函数

采用密度泛函理论的B3LYP方法和二次组态相互作用(QCISD(T))方法优化计算了OH分子基态(X2Ⅱ)的平衡结构、振动频率和离解能.根据原子分子反应静力学原理,导出了OH分子基态(X2Ⅱ)的合理离解极限,采用最小二乘法拟合Murrell-Sorbie函数得到了相应的势能函数和与该基态相对应的光谱常数(Be,αe,ωe和ωe xe),计算结果与实验数据符合得相当好.     

BF~X(X=-1,0,+1)分子离子基态的结构与势能函数研究

本文利用CCSD 方法,分别选用6-311++g(3df,3pd)、6-311++g(2df,2pd)和6-311++g(df,pd)基组对BF分子和BF~+、BF~-离子基态进行了几何优化和频率计算,并进行了单点能扫描计算.用最小二乘法拟合得到了BF~X(X=-1,0,+1)分子离子基态的Murrell-Sorbie势能函数.与实验及理论结果比较表明,本文对BF分子和BF~+离子基态光谱常数(B_e,α_e,ω_e,ω_ex_e)的计算结果达到了很高的精度.文章还首次给出BF~-离子基态的光谱常数(B_e,α_e,ω_e,ω_ex_e)和力常数(f_2,f_3,f_4),这将为BF~-离子基态的后期研究提供重要参考.研究表明:BF~X(X=-1,0,+1)分子离子基态的势能曲线均具有对应于稳定平衡结构的极小点,说明BF~X(X=-1,0,+1)分子离子基态是稳定存在的.     

BeH~+(X~1∑~+)离子势能函数及其分子常数研究

本文利用CCSD(T)方法和系列相关一致基,对BeH~+(X~1∑~+)离子的几何结构进行了优化,结果发现在CCSD(T)/aug-cc-pV5Z理论水平下得到的光谱数据(R_e=0.13142 nm,ω_e=2212.7 cm~(-1),D_e=3.1750 eV)与实验值非常接近.在CCSD(T)/aug-cc-pV5Z理论水平下又对BeH~+(X~1∑~+)离子的势能曲线进行了计算,再用最小二乘法将计算结果拟合成了Murrell-Sorbie函数.利用拟合出的解析势能函数,进一步计算出了BeH~+离子X~1∑~+态的其它光谱常数(B_e,α_e,ω_e和ω_ex_e),且与实验及其它理论计算结果进行了比较.以得到的解析势能函数为基础,通过求解双原子分子核运动的径向Schr(o|¨)dinger方程,找到了J=0时基态的全部20个振动态,并求出了每一振动态的振动能级、转动惯量及离心畸变常数(D_v,H_v,L_v,M_v,N_v,O_v).计算结果与实验数据的比较表明,BeH~+(X~1∑~+)离子的势能函数可用Murrell-Sorbie函数来表达,而且由此计算出的光谱常数、振动能级和转动惯量等都达到了相当高的精度.     

LaF分子结构与基态X1Σ+势能曲线研究

用能量一致相对论有效核芯势和含极化函数4f2g和弥散函数1s1p1d的价基组, 在各种计算水平上计算了LaF分子结构、振动频率和离解能. 根据原子分子反应静力学原理导出LaF分子基态可能的电子状态和离解极限, 用密度泛函理论中的B3LYP方法计算了基态X1Σ+势能曲线, 拟合得到了Murrell-Sorbie解析势能函数及其在平衡位置附近的Dunham展开式, 由此计算的振转常数和实验光谱数据完全吻合. 得到的解析势能函数可用于计算振转光谱精细跃迁结构和原子分子碰撞反应动力学过程, 具有重要的实用意义.     

LaCl分子结构与基态X1Σ+势能函数

用能量一致相对论有效核芯势和参阅文献基础上添加极化函数4f2g的价基组,在密度泛函理论(DFT)、多体微扰MPn和组态相关理论QCISD水平上计算了LaCl分子结构、离解能和振动频率.根据原子分子反应静力学原理,导出LaCl分子基态可能的电子状态和离解极限,用DFT中的B3LYP方法计算了基态X1Σ+势能曲线,拟合得到了MurrellSorbie解析势能函数及其在平衡位置附近的Dunham展开式,由此计算的振转常数与实验光谱数据完全符合.得到的解析势能函数可用于计算振转光谱精细跃迁结构和原子分子碰撞反应动力学过程 关键词： LaCl 相对论有效核芯势 解析势能函数 振转光谱常数     

icMRCI方法研究NS~±离子体系基态光谱

本文采用高精度的内收缩多参考组态相互作用方法(icMRCI)计算了NS~±体系基态的势能曲线,为了能够获得精确结果在计算过程中考虑了能量的Davidson修正.之后基于获得的势能曲线求解核的一维Schr?dinger方程,得到了NS~±离子体系基态的光谱数据R_e、ω_e、ω_eχ_e、B_e、α_e.发现本文理论计算结果与已有的实验数据和现有理论值吻合得很好.并进一步计算了NS~+(X~1Σ~+)基态和NS~-(X~3Σ~-)基态的振动能级G(ν)和体系转动量子数J=0时的分子离心畸变常数B_ν、D_ν.与实验数据和其他理论结果的比较表明本文计算结果达到了较高精度能够为这一离子体系的进一步研究提供参考依据.     

LaF分子基态X1Σ+分析势能函数计算

用原子分子反应静力学原理导出LaF分子可能的电子状态和离解极限.在相对论有效核芯势RECP(Relativistic Effective Core Potential)近似下,用密度泛函理论中的B3LYP方法优化了LaF分子单、三重态平衡几何结构,计算了基态X1Σ+的振动基频和离解能.在计算出来的一系列单点势能基础上,用非线性最小二乘方法拟合出基态Murrell-Sorbie势能曲线,得到分析势能函数,由此计算出相应光谱常数ωe、Be、αe、ωeχe的理论值并和实验测量的振转光谱比较,结果非常吻合.另外还比较了用两种不同有效势得到的分析势能函数和光谱参数,以能量一致相对论有效势ECEP(Energy Cosistent Relativistic Effective Potential)得到的结果最好.     

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.     

Electron-phonon interaction effects on the surface states in wurtzite nitride semiconductors

A variational approach is used to study the surface states of an electron in a semi-infinite wurtzite nitride semiconductor. The surface-state energy of the electron is calculated, by taking the effects of the electron-surface optical phonon interaction and structure anisotropy into account. The numerical computation has been performed for the energies of the electronic surface states as a function of the surface potential V₀ for wurtzite GaN, AlN, and InN, respectively. The results show that the electron-phonon interaction lowers the surface state energy. It is also found that the energies of the electronic surface-state in wurtzite structures are lower than that in the zinc-blende structures by hundreds of meV for the materials calculated. The influence of e-p-interactions on the surface state of electron cannot be neglected.     

OD、OT、DT分子基态的结构和解析势能函数

本文采用密度泛函方法(B3LYP)和组态相关方法(QCISD(T))优化计算了OD、OT、DT分子基态(X2Ⅱ)的平衡结构、振动频率和离解能.根据原子分子反应静力学原理.导出了OD、OT、DT分子基态(X2 Ⅱ)的合理离解极限,采用最小二乘法拟合Murrell-Sorbie函数得到了相应的势能函数和与该基态相对应的光谱常数(Be,ae,we和wexe),计算结果与实验数据符合得相当好.     

Effect of electron–phonon interaction on surface states in wurtzite nitride semiconductors under pressure

A variational theory is proposed to study the electronic surface states in semi-infinite wurtzite nitride semiconductors under the hydrostatic pressure. The electronic surface state energy level is calculated, by taking the effects of the electron–Surface–Optical–phonon interaction, structural anisotropy and the hydrostatic pressure into account. The numerical computation has been performed for the electronic surface state energy levels, coupling constants and the average penetrating depths of the electronic surface state wave functions under the hydrostatic pressure for wurtzite GaN, AlN and InN, respectively. The results show that electron–Surface–Optical–phonon interaction lowers the electronic surface state energy levels. It is also found that the electronic surface state energy levels decrease with the hydrostatic pressure in wurtzite GaN and AlN. But for wurtzite InN, the case is contrary. It is shown that the hydrostatic pressure raised the influence of electron–phonon interaction on the electronic surface states obviously. The effect of electron–Surface–Optical–phonon interaction under the hydrostatic pressure on the electronic surface states cannot be neglected, in specially, for materials with strong electron–phonon coupling and wide band gap.     

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

The equilibrium geometries, potential energy curves, spectroscopic dissociation energies of the ground and low-lying electronic states of He₂, He₂⁺ and He₂⁺⁺ 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 B_e, α _e, ω _e, and ω _e χ _e 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 X¹Σ_g⁺ of He₂⁺⁺ energy curve are explained using the avoided crossing rules of valence bond model.     

The charge neutrality level and the fermi level pinning in A<Superscript>3</Superscript>N (BN,AlN, GaN,InN) nitrides

The electronic band structure and position of the charge neutrality level (CNL) in BN, AlN, GaN, and InN compounds with cubic and hexagonal lattices are calculated within the density functional theory (DFT-GGA). It is shown that the charge neutrality level is shifted from the middle of the BN and AlN forbidden band to the upper half of the GaN forbidden band and to the allowed energy region in the InN conduction band as the cation atomic weight increases. This determines semiinsulating properties of BN and AlN, n-type conductivity of GaN, and n ⁺-type conductivity of InN upon saturation of these materials by intrinsic lattice defects due to hard radiation. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 24–31, December, 2008.     

Stability and electronic structure of single-walled InN nanotubes

Based on density functional theory calculations, we predict the stability and electronic structures of single-walled indium nitride (InN) nanotubes. Compared with other group III-nitride nanotubes with a similar diameter, strain energies of InN nanotubes relative to their graphitic sheet are the lowest, suggesting the possibility of the formation of InN nanotubes. Considering the stability of a graphitic InN sheet, InN nanotubes are in metastable states with the stability between GaN nanotubes and AlN nanotubes. Contrary to the case of carbon nanotubes and BN nanotubes, the bond-length of both horizontal and vertical In–N bonds in InN nanotubes decreases as the tube diameter increases. InN nanotubes are all semiconductors with an almost constant band gap of about 1 eV. The existence of a direct gap in zigzag InN nanotubes and the small band gap indicate that they may have potential applications in light emitting devices and solar cells.     

On the potential energy curves of LaO molecule

Turning points for several electronic states of LaO molecule are calculated using the Rapid method by Morse function, and compared with those obtained by RKR method. The electronegativity potential function and RKR potential functions are compared for the ground state of the molecule and an estimate of dissociation energy of LaO molecule in the ground state is reported.     

InAlN/GaN异质结二维电子气波函数的变分法研究

使用变分法推导了InAlN/GaN异质结二维电子气波函数和基态能级的解析表达式,并讨论了InAlN/GaN异质结结构参数对二维电子气电学特性的影响.在假设二维电子气来源于表面态的前提下,使用了一个包含两个变分参数的尝试波函数推导电子总能量期望值,并通过寻找能量期望极小值确定变分参数.计算结果显示,二维电子气面密度随InAlN厚度的增大而增大,且理论结果与实验结果一致.二维电子气面密度增大抬高了基态能级与费米能级,并保持二者之差增大以容纳更多电子.InAlN/GaN界面处的极化强度失配随着In组分增大而减弱,二维电子气面密度随之减小,并导致基态能级与费米能级减小.所建立的模型能够解释InAlN/GaN异质结二维电子气的部分电学行为,并为电子输运与光学跃迁的研究提供了解析表达式.