State-of-the-Art Calculations of Sublimation Enthalpies for Selected Molecular Crystals and Their Computational Uncertainty
State-of-the-Art Calculations of Sublimation Enthalpies for Selected Molecular Crystals and Their Computational Uncertainty
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DOI：
10.1021/acs.jctc.7b00164
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发表时间：
2017-06-01
影响因子：
5.5
通讯作者：
Fulem, Michal
中科院分区：
文献类型：
--
作者：
Cervinka, Ctirad;Fulem, Michal
发展了一种从第一性原理计算分子晶体升华热的计算方法，并与经过严格评价的文献实验数据进行了比较。计算了一组选定的22个分子晶体的低温相升华热随温度的变化。计算方法由基于量子化学和统计热力学的高级电子结构方法的几个积木组成。采用从头算方法，通过迭代处理单激发和双激发，微扰三重校正和估计的完整基组描述[CCSD(T)/CBS]，直到耦合的团簇，计算基于片段的加法方案中晶相的结合能。结合周期边界条件(PBC)和准谐近似的密度泛函理论(DFT)计算，计算了热对固相热的贡献。在理想气体模型中，用刚性转子谐振子模型计算了汽相的性质，内旋转修正采用一维受阻转子近似，并适当处理了分子在0K附近的转动自由度，讨论了作为温度函数的升华热的所有单项，并通过与严格评价的实验数据的比较，估计了它们的不确定度。
A computational methodology for calculation of sublimation enthalpies of molecular crystals from first principles is developed and validated by comparison to critically evaluated literature experimental data. Temperature-dependent sublimation enthalpies for a set of selected 22 molecular crystals in their low-temperature phases are calculated. The computational methodology consists of several building blocks based on high-level electronic structure methods of quantum chemistry and statistical thermodynamics. Ab initio methods up to the coupled clusters with iterative treatment of single and double excitations and perturbative triples correction with an estimated complete basis set description [CCSD(T)/CBS] are used to calculate the cohesive energies of crystalline phases within a fragment-based additive scheme. Density functional theory (DFT) calculations with periodic boundary conditions (PBC) coupled with the quasi-harmonic approximation are used to evaluate the thermal contributions to the enthalpy of the solid phase. The properties of the vapor phase are calculated within the ideal-gas model using the rigid-rotor harmonic-oscillator model with correction for internal rotation using a one-dimensional hindered rotor approximation and a proper treatment of the molecular rotational degrees of freedom in the vicinity of 0 K. All individual terms contributing to the sublimation enthalpy as a function of temperature are discussed and their uncertainties estimated by comparison to critically evaluated experimental data.