Exclusively Relativistic: Periodic Trends in the Melting and Boiling Points of Group 12

First-principles simulations can advance our understanding of phase transitions but are often too costly for the heavier elements, which require a relativistic treatment. Addressing this challenge, we recently composed an indirect approach: A precise incremental calculation of absolute Gibbs energies for the solid and liquid with a relativistic Hamiltonian that enables an accurate determination of melting and boiling points (MPs and BPs). Here, we apply this approach to the Group 12 elements Zn, Cd, Hg, and Cn, whose MPs and BPs we calculate with a mean absolute deviation of only 5 % and 1 %, respectively, while we confirm the previously predicted liquid aggregate state of Cn. At a non-relativistic level of theory, we obtain surprisingly similar MPs and BPs of 650 +/- 30 K and 1250 +/- 20 K, suggesting that periodic trends in this group are exclusively relativistic in nature. Ultimately, we discuss these results and their implication for Groups 11 and 14.

Automated summary

In this study, an indirect approach was developed to accurately calculate the absolute Gibbs energies of solid and liquid phases of Group 12 elements using a relativistic Hamiltonian, resulting in precise determination of melting and boiling points. The calculated mean absolute deviation for melting and boiling points was only 5% and 1% respectively, with confirmation of liquid aggregate state of Cn. Additionally, the results indicated that periodic trends in this group are primarily influenced by relativistic effects.