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arXiv · 2512.12338

Shape descriptors of equilibrium states in a quantum lattice model with local multi-well potentials: A geometric analysis near the phase transitions in Sn$_2$P$_2$S$_6$ ferroelectric crystals

S. Özüm·T. Akkurt·R. Erdem·N. Güçlü
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Abstract

We analyze the equilibrium states of quantum lattice model with local multi-well potentials for Sn$_2$P$_2$S$_6$ ferroelectric crystals using the mean and Gaussian curvatures ($H$, $K$), curvedness ($C$) and shape index ($S$). From the energy gap, pressure and temperature variations of $H$, $K$, $C$ and $S$, we have reported the geometric construction of the free energy surfaces for the ferroelectric and paraelectric phases. Their behaviors are explicitly observed near the ferroelectric-paraelectric phase transitions. It is found that $H$, $C$ and $S$ display a cusp singularity at the criticality while $K$ converges to zero on both sides of the critical and tricritical points.

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S. Özüm, T. Akkurt, R. Erdem, N. Güçlü. 2025-12-13. Shape descriptors of equilibrium states in a quantum lattice model with local multi-well potentials: A geometric analysis near the phase transitions in Sn$_2$P$_2$S$_6$ ferroelectric crystals. https://doi.org/10.5488/cmp.28.43703

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