Field-Commandeered Paralattices in 2D Ice: Sub-Ambient Lockdown Across Thermal Frontiers

The discovery of novel two-dimensional (2D) water/ice not only expands the boundaries of conventional states of matter but also reveals transformative potential for fundamental science and applied technologies. However, significant challenges remain in the geometric regularity design, scalable and precise fabrication, stable characterization, and practical application of these structures. This study focuses on the self-assembly behavior of unsaturated water molecules under the synergistic action of interfacial confinement and an applied directional electric field. Combining molecular dynamics simulations and first-principles calculations, we reveal a novel interfacial 2D parallelogram water lattice that can exist stably at both room temperature and cryogenic temperatures. To overcome fabrication bottlenecks, we propose a synergistic strategy employing a "limited-quantity & confined-space dual-control method" combined with directional electric field regulation. This strategy enables the precise and scalable preparation of 2D water/ice structures with consistent orientation and geometric order. Our findings demonstrate that under the synergistic conditions of a low-density aqueous environment, narrow-spaced interfacial confinement, and a directional electric field, water molecules spontaneously assemble into a 2D parallelogram lattice. The lattice orientation is precisely controlled by the direction of the electric field applied parallel to the interface. At room temperature, applying the electric field induces the formation of a highly ordered lattice structure; however, this orientational consistency vanishes immediately upon field removal. In contrast, at sub-ambient temperatures, the electric field induces a similarly ordered lattice, but crucially, the orientational consistency persists even after the field is withdrawn. Notably, in near-sub-ambient environments where molecular thermal motion is reduced, the formation of the ordered lattice can be achieved with a relatively small applied electric field. As the temperature decreases further, a stronger field is required to drive the ordering process. The field strength exhibits a significant negative correlation with system pressure, a universal relationship observed across both room temperature and cryogenic regimes. Increasing field strength systematically reduces the water layer thickness, clearly revealing the field-induced molecular ordering and structural densification. However, the system's total energy change is governed by competing mechanisms, including orientational energy, hydrogen-bond reconstruction energy, adsorption energy, and field-induced energy storage. This complexity results in a distinct non-monotonic thermodynamic response between the applied field voltage and the total system energy, with markedly different behaviors observed across different temperature ranges. The 2D parallelogram water lattice unveiled in this work represents a novel structure discovered under low-pressure interfacial confinement, challenging the conventional rules governing liquid water and ice phases. Its unique hydrogen-bond network and geometric arrangement not only open new perspectives for fundamental studies of physical properties but also hold breakthrough potential for technological applications. This discovery significantly enriches the knowledge base for constructing geometrically regular 2D materials based on weak interactions, extending beyond the realm of strong covalent, ionic, or metallic bonds. The "dual-control method + directional electric field regulation" strategy proposed herein provides a pioneering theoretical framework and experimental pathway for the scalable, controlled fabrication of 2D water/ice.