Theory and Simulation

Major Contribution to Research

The theory/simulation effort is focusing on developing key simulation capabilities of general use at the 2DCC and beyond in modeling and understanding growth of 2D chalcogenides. Reactive force field development, guided by first-principles expertise and accelerated by advance sampling techniques, will expand the capabilities of these force fields to handle precursor chemistry and substrate interactions. Additional efforts will target mass and heat transport to the substrate surface, computational thermochemistry to model phase equilibria during synthesis, and development of theoretical tools and results for the interpretation of in situ characterization probes (e.g. optical spectra, scanned probe, electron microscopy). The over-arching goal here is to develop simulation tools that will enable key insights into kinetic growth processes, within broader thermodynamic constraints, and to make both tools and results available for broad use, both anticipating future experimental needs and reacting to current experimental needs.

Capability and Unique Aspects

The 2DCC has unique capabilities in the Theory/Simulation facility by virtue of the combined capabilities of the 2DCC theory team – which covers multiple aspects of materials computation – and the underpinning technical capabilities of the Materials Computation Center (MCC) and the Institute for CyberScience – Advanced Cyberinfrastructure (ICS-ACI) at Penn State.

MCC – The MCC supports simulations of materials across multiple length and time scales, with technical support of advanced simulation software. The 2DCC is implementing, in partnership with the MCC, an integrated suite of software tools, hardware resources, and computational expertise to support direct simulation of key processes during materials growth, to suggest routes to overcome experimental obstacles, to assist in the interpretation of in situ characterization and post-synthesis measurement of samples, and also to predict new synthesis targets. 2DCC users will have access to MCC capabilities in computational methods including first-principles techniques at the density functional level (Quantum Espresso, VASP, etc.) and powerful empirical methods that can model complex reaction pathways over long time scales and length scales at both atomistic (ReaxFF) and phase-field levels.

ICS-ACI – One layer below MCC in the high-performance computation stack is the ICS-ACI, which acquires, hosts, and supports high-performance computational hardware and software. 2DCC computational resources will reside and be maintained by ICS-ACI. The ICS-ACI central facility serves the entire campus and is located at Penn State’s University Park Campus in the Penn State Data Center. The total computational resource of the ICS-ACI currently include:

  • Compute Resources - 23,000 basic-, standard- and high-memory nodes (128 GB, 256 GB, and 1 TB) with dual 10- or 12-core Xeon E5-2680 processors.
  • Storage - Over 2.5 PB of network-attached storage (NAS) to support users’ Home, Work, and Group storage needs and 2.5 PB of general parallel file system (GPFS) for Scratch storage in addition to 4 PB of tape storage for backup purposes. 
  • Network - High-performance Network Fabric built on Brocade VCS fabric technology. The architecture employs a research-centric software stack and customized environments allow researchers to deploy software from pre-compiled and tested software catalogs. The software stack supports both commercial and Opensource software.