Sudolská Mária, Cantrel Laurent, Cernušák Ivan
Department of Physical and Theoretical Chemistry, Faculty of Natural Sciences, Comenius University, Mlynská dolina, 84215, Bratislava, Slovakia,
J Mol Model. 2014 Apr;20(4):2218. doi: 10.1007/s00894-014-2218-4. Epub 2014 Apr 9.
Structure and thermodynamic properties (standard enthalpies of formation and Gibbs free energies) of hydrated caesium species of nuclear safety interest, Cs, CsOH, CsI and its dimer Cs₂I₂, with one up to three water molecules, are calculated to assess their possible existence in severe accident occurring to a pressurized water reactor. The calculations were performed using the coupled cluster theory including single, double and non-iterative triple substitutions (CCSD(T)) in conjunction with the basis sets (ANO-RCC) developed for scalar relativistic calculations. The second-order spin-free Douglas-Kroll-Hess Hamiltonian was used to account for the scalar relativistic effects. Thermodynamic properties obtained by these correlated ab initio calculations (entropies and thermal capacities at constant pressure as a function of temperature) are used in nuclear accident simulations using ASTEC/SOPHAEROS software. Interaction energies, standard enthalpies and Gibbs free energies of successive water molecules addition determine the ordering of the complexes. CsOH forms the most hydrated stable complexes followed by CsI, Cs₂I₂, and Cs. CsOH still exists in steam atmosphere even at quite high temperature, up to around 1100 K.
为评估在压水堆严重事故中可能存在的核安全相关水合铯物种（Cs、CsOH、CsI及其二聚体Cs₂I₂），计算了含有一至三个水分子时它们的结构和热力学性质（标准生成焓和吉布斯自由能）。计算采用耦合簇理论，包括单、双和非迭代三取代（CCSD(T)），并结合为标量相对论计算开发的基组（ANO-RCC）。使用二阶无自旋道格拉斯-克罗尔-赫斯哈密顿量来考虑标量相对论效应。这些相关的从头算计算得到的热力学性质（恒压下的熵和热容量作为温度的函数）用于使用ASTEC/SOPHAEROS软件进行的核事故模拟。连续添加水分子的相互作用能、标准焓和吉布斯自由能决定了配合物的排序。CsOH形成水合程度最高的稳定配合物，其次是CsI、Cs₂I₂和Cs。即使在相当高的温度下，高达约1100K，CsOH仍存在于蒸汽气氛中。
