Cubic wavefunction deformation of compressed atoms

TL;DR

This paper proposes that atomic wavefunctions deform under extreme pressures in non-metallic crystals, reducing symmetry and affecting physical properties, with implications for materials and neutron star matter.

Contribution

It introduces a variational model for atomic wavefunction deformation under high pressure and analyzes its effects on crystal structure and properties.

Findings

Deformation energy cost for Helium is about 25%.

Deformation reduces shear modulus and modifies atomic form factors.

Pressure thresholds for deformation are estimated.

Abstract

We hypothesize that in a non-metallic crystalline structure under extreme pressures, atomic wavefunctions deform to adopt a reduced rotational symmetry consistent with minimizing interstitial space in the crystal. We exemplify with a simple numeric variational calculation that yields the energy cost of this deformation for Helium to 25%. Balancing this with the free energy gained by tighter packing we obtain the pressures required to effect such deformation. The consequent modification of the structure suggests a decrease in the resistance to tangential stress, and an associated decrease of the crystal's shear modulus. The atomic form factor is also modified. We also compare with neutron matter in the interior of compact stars.