二电子系列关联能的并行计算

用组态相互作用方法计算了二电子体系电子关联能,为了获得高精度的结果往往需要巨大的计算量,以往单个处理器上的串行计算通常存在着机时长,内存不够的严重困难,为此采用并行分块消去迭地,同时在多个处理器上并行计算,得到了了基态关联能。     

聚对苯乙炔的能带结构和关联能计算

在考虑电子-电子相互作用情况下,对基态非简并聚合物聚对苯乙炔(PPV)的长程关联能进行了理论计算,并用长程关联能对带隙进行修正,最后讨论了长程关联能对带隙的影响.在对PPV链的计算中发现,长程关联能先会随着链长N的增加而减小,但当链长大于10个PPV单元后,长程关联能会达到饱和.与由Hartree-Fock(HF)方法所得的能隙宽度比.长程关联能的修正会使得能隙降低,这种修正后的能隙宽度与实验结果一致.     

聚对苯乙炔的能带结构和关联能计算

在考虑电子-电子相互作用情况下,对基态非简并聚合物聚对苯乙炔（PPV）的长程关联能进行了理论计算,并用长程关联能对带隙进行修正,最后讨论了长程关联能对带隙的影响。在对PPV链的计算中发现,长程关联能先会随着链长N的增加而减小,但当链长大于10后长程关联能会达到饱和。在链长为20个单元的PPV计算中,长程关联能的修正会降低由Hartree-Fock(HF)方法所得的能隙宽度。修正后的能隙宽度能很好的接近实验结果。     

聚乙炔的能带结构和长程关联能的计算

本文计算了在考虑电子-电子Coulomb相互作用情况下的导电聚合物聚乙炔的长程关联能（分周期边界条件和自然边界条件两种情况），与用其它方法得到的结果进行比较，结果符合很好，并且讨论了关联能对带隙的影响。     

长程电子关联对有限长聚乙炔链中极化子态的影响

本文采用扩展Hubbard模型, 加上长程关联哈密顿量,在自然边界条件下用自洽场方法研究了有限长反式聚乙炔链中极化子的问题。计算了长程电子关联对极化子的影响并计算了极化子的长程关联能。计算发现长程电子关联使极化子的位形变宽变浅(局域性减弱),在极化子区域,长程电子关联能比平均长程电子关联能要大。当链长增加到100格点以上时,电子极化子和空穴极化子的平均关联能趋于-0.1663eV,而在极化子区域,电子极化子和空穴极化子的平均关联能趋于-0.1868eV。     

长程电子关联对有限长聚乙炔链中极化子态的影响

本文采用扩展Hubbard模型,加上长程关联哈密顿量,在自然边界条件下用自洽场方法研究了有限长反式聚乙炔链中极化子的问题.计算了长程电子关联对极化子的影响并计算了极化子的长程关联能.计算发现长程电子关联使极化子的位形变宽变浅(局域性减弱),在极化子区域,长程电子关联能比平均长程电子关联能要大.当链长增加到100格点以上时,电子极化子和空穴极化子的平均关联能趋于-0.1663eV,而在极化子区域,电子极化子和空穴极化子的平均关联能趋于-0.1868 eV.     

聚合物中长程关联能的动力学研究

本文计算采用扩展的SSH哈密顿模型, 加上长程关联哈密顿量,在自然边界条件下,用绝热动力学方法研究了有限长反式聚乙炔链中平均关联能随时间的演化,计算了长程电子关联对极化子动力学的影响并计算了极化子状态下的长程关联能。结果发现,加入一个电子或空穴,平均关联能的大小随着时间呈非周期性阻尼振荡,经过一定时间后,平均关联能趋近一个恒定值,此时得到比较稳定的极化子位形。当格点增加时,长程关联能趋于恒定的时间逐渐缩短。     

氢负离子H^—关联能的B splines计算

对用Ｂｓｐｌｉｎｅｓ构造有限正交基矢集的方法进行了讨论，并计算了氢负离子Ｈ－的关联能，使得在合理的计算量范围内，总能量可以达到很高的精度，比常用的Ｓｌａｔｅｒ基计算结果提高了一个数量级。结果表明：Ｂｓｐｌｉｎｅｓ方法可以有效用于电子关联能的计算。     

聚合物中长程关联能的动力学研究

本文计算采用扩展的SSH哈密顿模型,加上长程关联哈密顿量,在自然边界条件下,用绝热动力学方法研究了有限长反式聚乙炔链中平均关联能随时间的演化,计算了长程电子关联对极化子动力学的影响并计算了极化子状态下的长程关联能.结果发现,加入一个电子或空穴,平均关联能的大小随着时间呈非周期性阻尼振荡,经过一定时间后,平均关联能趋近一个恒定值,此时得到比较稳定的极化子位形.当格点增加时,长程关联能趋于恒定的时间逐渐缩短.     

聚乙炔的能带结构和长程关联能的计算

本文计算了在考虑电子-电子Coulomb相互作用情况下的导电聚合物聚乙炔的长程关联能(分周期边界条件和自然边界条件两种情况),与用其它方法得到的结果进行比较,结果符合很好,讨论了关联能对带隙的影响.     

He_2~+团簇结构和解析势能函数的从头计算研究

采用从头计算的耦合簇方法CCSD(T)和He原子Dunning’s相关调和基函数组对He+2 团簇的结构参数、势能曲线进行计算。利用Murrell Sorbie函数和最小二乘法拟合出了解析势能函数 ,并以此为基础计算出光谱常数。通过比较发现 :分子结构和光谱常数计算结果均与实验值符合良好 ,优于文献报道的结果。说明本文所得势能函数解析表达式准确反映了分子中原子间相互作用 ,可用于更广泛的研究     

Shear viscosity of a simple fluid over a wide range of strain rates

The shear viscosity of the Weeks—Chandler—Andersen (WCA) fluid at the Lennard-Jones triple point has been calculated over a wide range of strain rates using the transient time correlation function (TTCF) formalism. It has been demonstrated that these calculations can be carried out at arbitrarily low strain rates with the precision of the Green—Kubo calculations. At high strain rates, the calculated data agree within the error bars with more precise data acquired using the computationally less demanding steady state (SS) non-equilibrium molecular dynamics (NEMD) method. The linear variation of viscosity with the square root of the strain rate is discussed.     

He+2团簇结构和解析势能函数的从头计算研究

采用从头计算的耦合簇方法CCSD(T)和He原子Dunning's相关调和基函数组对He+2团簇的结构参数、势能曲线进行计算.利用Murrell-Sorbie函数和最小二乘法拟合出了解析势能函数,并以此为基础计算出光谱常数.通过比较发现:分子结构和光谱常数计算结果均与实验值符合良好,优于文献报道的结果.说明本文所得势能函数解析表达式准确反映了分子中原子间相互作用,可用于更广泛的研究.     

Electrostatic interactions between molecules from relaxed one-electron density matrices of the coupled cluster singles and doubles model

The influence of electron correlation on the electrostatic interaction between closed shell molecules is studied using the relaxed electron densities of the coupled cluster singles and doubles (CCSD) model. The corresponding CCSD one-electron density matrices are efficiently computed without full four-index transformation by employing the generalized exchange and Coulomb operator technique. Using several representative van der Waals and hydrogen bonded complexes it was found that in most cases the convergence of the M?ller-Plesset expansion of the electrostatic energy, restricted to single, double and quadruple excitations, is satisfactory and the fourth-order triple excitation term is more important than the sum of the fifth- and higher-order contributions from CCSD theory. The importance of the CCSD correlation correction to the electrostatic energy was gauged by comparison of the total interaction energy computed by symmetry-adapted perturbation theory (SAPT) and by the super-molecular CCSD(T) approach (coupled cluster singles and doubles model with a non-iterative inclusion of triple excitations). Except for the CO and N₂ dimers, very good agreement between the two sets of results is observed. For the difficult case of the CO dimer the difference between the SAPT and CCSD(T) results can be explained by the truncation of the SAPT expansion for the dispersion energy at second order in the intramonomer correlation operator.     

基于相关系数特性的实时匹配算法

提出了一种高精度的快速匹配算法。其基本思想是根据相关系数矩阵的特性来动态改变相关搜索步长的。对于已知目标特性和点扩展函数的情况,求出其理想情况下的相关系数矩阵函数,确定可信阈值和搜索步长;对于不知道目标特性和点扩展函数的情况,通过相关系数矩阵拟合函数或简单变步长法来确定可信阈值和搜索步长。在得到相关系数最大值后,拟合得到亚像素定位精度。与一般相关方法比较,该方法具有定位精度高、稳健性强和运算速度快等优点。     

Double photoionization of helium down to 100 meV above threshold

Double photoionization of helium has been studied using a new instrument which allows one to detect the two emitted electrons over 4 pi steradians and measure their individual momenta. The experiments have been performed at 0.2 and 0.1 eV above threshold, and both double and triple differential cross sections have been extracted. In comparison with higher energy data, the results show that the strength of angular correlation between the two electrons increases towards threshold.     

利用相关技术测量激光脉冲的对比度

研究了在放大激光脉冲的噪声测量中，二阶相关技术和三阶相关技术的差别。理论分析显示，三阶相关技术不仅可以显示噪声脉冲的正确位置，而且具有比二阶相关技术更高的测量精度，数值计算也验证了这一点。     

基于多参考组态方法研究MgI分子激发态的光谱

利用Davidson修正的内收缩多参考组态相互作用（ic-MRCI+Q）方法,结合相关一致全电子基aug-cc-pwCV5Z+DK作为Mg原子和相对论有效芯赝势基（aug-cc-pV5Z-PP）为I原子的计算基组,优化计算MgI分子5个低激发束缚电子态的势能曲线和偶极矩,计算中同时引入核价电子相关和相对论效应修正势能曲线.利用LEVEL8.0程序拟合修正的势能曲线,得到光谱常数、振动能级和分子常数等光谱性质,结果与近来的部分理论计算或实验值吻合得较好,提供了更多激发态的光谱性质.为进一步研究MgI分子高激发态的光谱和跃迁特性提供理论支持.     

Subtle errors in αs determination using “corrected data” of energy-energy asymmetry

For the determination of α_s in the process of hadron production from electron-positron annihilation at 35 GeV, the complete second-order QCD calculation is used to study the corrections to the so-called “corrected data” of the asymmetry of the energy-energy correlation function (Asy). It is found that the correction in the values of α_s using the asymmetry method can be quite large while that for the new method, the planar triple energy correlation (PTC), is negligible.     

Two-step digital image correlation for micro-region measurement

A method of two-step digital image correlation is well developed with more stable and reliable calculating technology, which consists of a simple searching method and an iterative correlation method. This new method can not only improve the calculating speed and the measuring accuracy, but also simplify the process of the experiment. In order to further increase the sensitivity of the technique, the sub-pixel reconstruction is performed in sub-image by utilizing the higher precision calculation of bicubic spline interpolation value method, and the accuracy of displacement is extended to better than 0.01 pixel; the strain resolution is limited to less than 0.0002 in micro-region. The above method is applied to quantify the micro-deformation of bimaterial sample and coating sample. The experimental results show that the method of two-step digital image correlation is a potential boon to investigations at extremely small-size scales.