A low-symmetry ground state of dense two-dimensional hydrogen
Abstract
Hydrogen under pressure is an extremely complex system featuring molecular dissociation, metallization, and anomalous melting. While bulk hydrogen has been studied for nearly a century, its two-dimensional counterpart remains unexplored. Using first-principles structural searches and relaxations in supercells containing up to 512 atoms, we identify ground-state structures of dense two-dimensional hydrogen showing no evidence of long-range crystalline order over the simulated length scales. Within density functional theory, these structures have lower enthalpy than all crystalline candidates considered over an intermediate pressure interval between molecular and atomic crystals. This preference already emerges with classical nuclei and persists as the supercell size increases, while the dominant structure-factor peaks grow substantially more slowly than in the crystalline reference phases. Although crystals with very large primitive cells cannot be rigorously excluded, these findings support the possibility of a disordered ground state and identify dense two-dimensional hydrogen as a promising setting for investigating competition between crystallization and structural disorder.
Related
- Ground-state entanglement and preserved dynamical symmetry in the interacting boson model
- Two-dimensional shelving spectroscopy of ultraviolet ground state transitions in dysprosium
- Low-Depth Initial-State Preparation for Ground-State Energy Estimation of Two-Dimensional Strongly Correlated Systems
- Ground-state properties of the two-dimensional SWAP spin-glass ensemble
- An Analytical Full-Dimensional Potential Energy Surface for the H + C3H8 Hydrogen Abstraction Reaction: Non-Equivalence of the Primary Hydrogens and Variational Transition State Theory Kinetics
BibTeX
@misc{cozza2026lowsymmetry,
title = {{A low-symmetry ground state of dense two-dimensional hydrogen}},
author = {Cesare Cozza and Chris J. Pickard and Guglielmo Mazzola},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.22440},
eprint = {2609.22440},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.22440},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - A low-symmetry ground state of dense two-dimensional hydrogen
AU - Cesare Cozza
AU - Chris J. Pickard
AU - Guglielmo Mazzola
PY - 2026
DA - 2026/09/18
PB - arXiv
DO - 10.48550/arxiv.2609.22440
UR - https://arxiv.org/abs/2609.22440
AB - Hydrogen under pressure is an extremely complex system featuring molecular dissociation, metallization, and anomalous melting. While bulk hydrogen has been studied for nearly a century, its two-dimensional counterpart remains unexplored. Using first-principles structural searches and relaxations in supercells containing up to 512 atoms, we identify ground-state structures of dense two-dimensional hydrogen showing no evidence of long-range crystalline order over the simulated length scales. Within density functional theory, these structures have lower enthalpy than all crystalline candidates considered over an intermediate pressure interval between molecular and atomic crystals. This preference already emerges with classical nuclei and persists as the supercell size increases, while the dominant structure-factor peaks grow substantially more slowly than in the crystalline reference phases. Although crystals with very large primitive cells cannot be rigorously excluded, these findings support the possibility of a disordered ground state and identify dense two-dimensional hydrogen as a promising setting for investigating competition between crystallization and structural disorder.
ER -