Structural Evolution of C₆₀ Molecular Crystal Predicted by Neural Network Potential

Abstract

The preparation of fullerene and a wide range of derivatives has attracted much attention in past decades. Understanding the structural evolution starting from fullerene is critical to guide the experimental exploration but has been paid less attention yet. Using ab initio molecular dynamics or global structural search algorithm accompanied with density functional theory calculations can give a glance of the potential energy surface (PES), but suffers high cost and low efficiency. Herein, by using neural network potentials and stochastic surface walking global structural search method, an accelerated energy calculation, and the higher efficient PES mapping starting from C 60 molecular crystal are reported. The structural evolution is found to follow an order of molecular crystal → polymers → opened caged ordered structures → 3D) curved carbon and graphite under zero pressure. Under high pressures, e.g., 50 GPa, the evolution follows a pathway of fullerene → sp 2 and sp 3 hybrid carbon → sp 3 amorphous carbon and crystal diamond. The electronic property calculation of the obtained structures in the evolution pathway shows a band gap depending on the order parameter of the generated structures, suggesting that more novel carbons can be potentially prepared in experiments, starting from C 60 .

Enhancement of short/medium-range order and thermal conductivity in ultrahard sp3 amorphous carbon by C70 precursor

“…The unique configuration of the C 70 precursor should be responsible for the amorphous structure formed, and for its superior properties. As we know, fullerene cages collapse under pressure, accompanied with sp 2 − sp 3 bonding changes 53 , 54 . In this case, from the topological transition point of view, the presence of both hexagons and pentagons makes formation of an ordered structure unlikely 30 , but overheating could induce re-crystallization and diamond formation, as observed in our comparison experiments.…”

Temperature-Dependent Paracrystalline Nucleation in Atomically Disordered Diamonds

“…14,15 Starting from precursors of C 60 , the structural evolution of atomically disordered diamonds by sp 2 to sp 3 hybridization and the corresponding pressure− temperature dependence were reported through simulations. 15,16 With an adiabatic-bias MD technique, 17 Tang et al also obtained p-D with paracrystalline fraction up to 70%, 15 successfully bridging the temporal gap between the experiment and simulation. However, the temperature effect on the formation of sp 3 -rich amorphous carbons is still ambiguous, further impeding us to fundamentally understand why atomically disordered sp 3 -hybridized carbons can be formed unexpectedly and how to obtain them under suitable HPHT conditions.…”

“…Recently, Shang et al and Tang et al coincidentally reported atomically disordered diamonds with a sp 3 concentration close to 100%. The synergistic control of high-pressure and high-temperature (HPHT) conditions in their experiments revealed that atomically disordered diamonds can be obtained only within a narrow temperature range. , Starting from precursors of C 60 , the structural evolution of atomically disordered diamonds by sp 2 to sp 3 hybridization and the corresponding pressure–temperature dependence were reported through simulations. , With an adiabatic-bias MD technique, Tang et al also obtained p-D with paracrystalline fraction up to 70%, successfully bridging the temporal gap between the experiment and simulation. However, the temperature effect on the formation of sp 3 -rich amorphous carbons is still ambiguous, further impeding us to fundamentally understand why atomically disordered sp 3 -hybridized carbons can be formed unexpectedly and how to obtain them under suitable HPHT conditions.…”

Long-range ordered porous carbon: A new carbon constructed by connecting C 60 cages

“…In recent reporting on Nature (https://www.nature.com/ articles/s41586-022-05532-0), Yanwu Zhu, Rodney S. Ruoff, and their colleagues have synthesized a crystalline porous carbon constructed with covalent connected broken C 60 cages through a facile electron injecting approach that can be easily scaled up [16]. The C 60 molecule is an electron-acceptor, and injecting electrons into C 60 molecules can promote their reactivity.…”