Electronic Structure and Molecular Chirality

在Breit-Pauli哈密顿量和广义自旋轨道的基础上，得到了自旋轨道耦合SCF（SOC-SCF）波函数，并将其用于计算手性分子的宇称破坏能E <pν>. SOC-SCF方法对L-丙氨酸两性酶（L-ALAZ）的构象变化的E <pν>值具有可靠的变异性。采用[5s 2 p/3s]基组对L-ALAZ水溶液进行了分析。溶剂化作用由广义Born公式的连续介质模型引入，E <pν>映射是NH_3基团的φ和CO_2基团的θ的函数。在（φ，θ）图中，正E &lt;p ν&gt;区比负E &lt;pν&gt;区宽，平均E &lt;pν&gt;值为+2.1 10 ^<20>hartree，表明L-ALAZ在水溶液中比D-ALAZ更不稳定，这是由于宇称破坏的弱中性流相互作用引起的，这一结论得到了Monte Carlo（MC）模拟和从头算自旋轨道耦合SCF（SOC-SCF）方法的支持.在对L-ALAZ水溶液的MC模拟中，每隔1 M步选取100个溶液结构，计算了每个溶液结构中L-ALAZ-（H2O）n（n=1-10）团簇的E &lt;pν&gt;能量。在298 K时，L-ALAZ在水溶液中的热稳定构象的E &lt;pν&gt;期望值为正值。MC/MO计算也提供了支持的不稳定的L-ALAZ相比，D-ALAZ在水溶液中的热可及的构象。

The spin-orbit-coupling SCF (SOC-SCF) wavefunction was obtained on the basis of Breit-Pauli Hamiltonian and generalized spin-orbitals and was used to calculate the parity-violating energy, E <pν> of chiral molecules. The SOC-SCF method gave a reliable variation in the E <pν> value for the conformational change of L-alanine zwitterion (L-ALAZ). The method with the [5s2p/3s] basis set was applied to L-ALAZ in aqueous solution. The solvation was introduced by the continuum model of generalized Born formula, and the E_<pν> map was created as a function of two torsion angles, φ for the NH_3 group and θ for the CO_2 group. In the (φ,θ) map of E_<pν> the positive E_<pν> area is wider than the negative one, and the averaged E_<pν> value was +2.1×10^<20> hartree, indicating that L-ALAZ is more unstable than D-ALAZ in aqueous solution due to the parity-violating weak neutral current interaction.This conclusion was supported by the Monte Carlo (MC) simulation and ab initio spin-orbit coupling SCF (SOC-SCF) method. The 100 solution structures were picked up at every 1M steps of the MC simulation of the L-ALAZ aqueous solution, and the E_<pν> energy was calculated for the L-ALAZ-(H_2O)_n (n=1-10) clusters in each solution structure. The expectation value of E_<pν> of L-ALAZ was calculated to be positive for thermally stable conformations in aqueous solution at 298K. The MC/MO calculations also provide support for the destabilization of L-ALAZ compared to D-ALAZ at thermally accessible conformations in aqueous solution.