  Individual phases are commonly considered as the building blocks of
materials. However, the accurate theoretical prediction of properties of
individual phases remains elusive. The top-down approach by decoding genomic
building blocks of individual phases from experimental observations is
non-unique. The density functional theory (DFT), as the state-of-the-art
solution of quantum mechanics, prescribes the existence of a ground-state
configuration at zero K for a given system. It is self-evident that the
ground-state configuration alone is insufficient to describe a phase at finite
temperatures as symmetry-breaking non-ground-state configurations are excited
statistically at temperatures above zero K. Our multi-scale entropy approach
(recently terms as Zentropy theory) postulates that the entropy of a phase is
composed of the sum of the entropy of each configuration weighted by its
probability plus the configurational entropy among all configurations.
Consequently, the partition function of each configuration in statistical
mechanics needs to be evaluated by its free energy rather than total energy.
The combination of the ground- and non-ground-state configurations represents
the building blocks of materials and can quantitively predict free energy of
individual phases with the free energies of ground- and non-ground-state
configurations predicted from DFT, plus all properties derived from free energy
of individual phases.
