The physics of solid carbon dioxide and its different polymorphs are not only of great practical and fundamental interest but also of considerable importance to terrestrial and planetary chemistry. Despite decades of computer simulations, the atomic-level structures of solid carbon dioxide polymorphs are still far from well understood and the phase diagrams of solid carbon dioxide predicted by traditional empirical force fields or density-functional theory are still challenged by their accuracies in describing the hydrogen bonding and van-der-Waals interactions. Especially the “intermediate state” solid carbon dioxide phase II, separating the most stable molecular phases from the intermediate forms, has not been demonstrated accurately and is the matter of a long standing debate. Here, we introduce a general ab initio electron-correlated method that can predict the Gibbs free energies and thus the phase diagrams of carbon dioxide phases I, II and III, using the high-level second-order Møller-Plesset perturbation (MP2) theory at high pressures and finite temperatures. The predicted crystal structures, phase transitions, and Raman spectra are in excellent agreement with the experiments. The proposed model not only reestablishes the position of solid carbon dioxide in phase diagram but also holds exceptional promise in assisting experimental studies of exploring new phases of molecular crystals with potentially important applications.

固体二氧化碳及其不同的多晶型物的物理学不仅具有重大的现实意义和根本意义，而且对地球化学和行星化学都具有相当重要的意义。尽管进行了数十年的计算机模拟，但固态二氧化碳多晶型物的原子级结构仍远未得到很好的理解，传统经验力场或密度泛函理论预测的固态二氧化碳的相图在描述碳纳米管的准确性时仍面临挑战。氢键和范德华力相互作用。特别是从中间形式中分离出最稳定的分子相的“中间状态”固态二氧化碳相II，尚未得到准确的论证，这是一个长期争论的问题。这里，我们介绍了一种通用的从头算电子相关的方法，该方法可以使用高阶二阶Møller-Plesset扰动（MP2）理论预测吉布斯自由能，从而预测二氧化碳相I，II和III的相图。压力和有限的温度。预测的晶体结构，相变和拉曼光谱与实验非常吻合。提出的模型不仅可以重新建立固态二氧化碳在相图中的位置，而且在协助实验研究具有潜在重要应用的分子晶体新相方面具有广阔的前景。在高压和有限温度下使用高级二阶Møller-Plesset微扰（MP2）理论。预测的晶体结构，相变和拉曼光谱与实验非常吻合。提出的模型不仅可以重新建立固态二氧化碳在相图中的位置，而且在协助实验研究具有潜在重要应用的分子晶体新相方面具有广阔的前景。在高压和有限温度下使用高级二阶Møller-Plesset微扰（MP2）理论。预测的晶体结构，相变和拉曼光谱与实验非常吻合。提出的模型不仅可以重新建立固态二氧化碳在相图中的位置，而且在协助实验研究具有潜在重要应用的分子晶体新相方面具有广阔的前景。