The Dynamical Ensemble of the Posner Molecule Is Not Symmetric

The Posner molecule, Ca9(PO4)6, has long been recognized to have biochemical
relevance in various
physiological processes. It has found recent attention for its possible
role as a biological quantum information processor, whereby the molecule
purportedly maintains long-lived nuclear spin coherences among its 31P nuclei (presumed to be symmetrically arranged), allowing
it to function as a room temperature qubit. The structure of the molecule
has been of much dispute in the literature, although the S6 point group symmetry has often been assumed and exploited
in calculations. Using a variety of simulation techniques (including ab initio molecular dynamics and structural relaxation),
rigorous data analysis tools, and by exploring thousands of individual
configurations, we establish that the molecule predominantly assumes
low-symmetry structures (Cs and Ci) at room
temperature, as opposed to the higher-symmetry configurations explored
previously. Our findings have important implications for the viability
of this molecule as a qubit.