Dr.   Hendrik     Heinz

Dr. Hendrik Heinz

Associate Professor
Department of Polymer Engineering
Phone: 330-972-7467
Email: hendrik.heinz@uakron.edu

The INTERFACE Force Field

The Heinz laboratory has developed all-atom force fields for simulations of nanostructures at the 1 to 100 nm scale in unprecendented accuracy, including minerals, metals, and oxides. The INTERFACE force field seemlessly integrates platforms for materials oriented simulations and for biomolecular simulations into one, thermodynamically consistent package for all compounds. In addition, an extensive database of surface models realistically covers defects and cation exchange capacities (e.g. clays), the full range of pH values and nanoparticle surface features (e.g. silica and apatites), as well as typical cleavage planes that are essential for meaningful predictions. DFT methods cannot describe the interactions at this length and time scale, and are often less accurate with respect to surface properties. Therefore, the INTERFACE force field and the surface model database aid in computation-guided discovery of bionanostructures and advanced materials, along with multi-scale combinations from quantum methods to continuum.

View Overview Presentation

The INTERFACE force field currently includes the PCFF-INTERFACE, CHARMM-INTERFACE, and CVFF-INTERFACE force fields that can be downloaded here and offer accurate parameters for the following compounds in addition to the paramaters for biomolecules, polymers, and solvents native to the respective force fields (see Heinz et al Langmuir 2013, 29, 1754).

  • Clay minerals
    Kaolinite, mica, montmorillonites of different cation density, pyrophyllite. Includes ready-to-use molecular models of periodic lattices and of cleaved surfaces with equilibrium distributions of cations. The spatial distribution of defect sites agrees with NMR data.
  • Fcc metals
    Ag, Al, Au, Cu, Ni, Pb, Pd, Pt.
    Includes ready-to-use models of unit cells and rectangular cells of different orientation. The cells facilitate an easy build of {111}, {100}, {110} surfaces and nanostructures such as nanorods and particles.
  • Silica
    Models of cristobalite and quartz as well as all types of silanol and siloxide-terminated surfaces. Includes ready-to-use models of Q2, Q3, Q4, and mixed-chemistry silica surfaces of different degree of ionization that represent specific pH values and silica nanoparticle sizes. Explanations how to choose models are included.
  • Hydroxyapatite
    Ready-to-use models of the unit cell and all common cleavage planes for specific pH values, as well as models of nanocrystallites and sodium hydrogen phosphate/dihydrogen phosphate buffer.
  • Cement minerals (extensive)
    Tricalcium silicate, tricalcium aluminate, ettringite, monosulfate, tobermorite 11 Å and tobermorite 14 Å.
    Includes ready-to-use models for each mineral, including unit cells, various hydrated phases, and different cleavage planes.
    (CVFF and CHARMM currently support tricalcium silicate and tricalcium aluminate only)
  • Calcium sulfates
    Calcium sulfate (anhydrite), calcium sulfate hemihydrate, and calcium sulfate dihydrate (gypsum).
    Includes models of the unit cells, from which cleavage planes can be easily constructed.
    (currently supported in PCFF only)
  • PEO (poly(ethylene oxide))
    Includes ready-to-use models of crystalline PEO and an example chain (MW ~2000 g/mol) in water, from which models of chains and copolymers of different length can be constructed.
    (currently supported in PCFF only)

The parameters for several compounds can also be implemented in other force fields such as AMBER, OPLS-AA, and Dreiding, e.g., fcc metals, apatite, silica, and some cement minerals. The following compilations are currently available for download including documentation:

(latest release)
2012-08-01 to 2010-03-01 CHARMM_METAL (same as CHARMM-INTERFACE with metals only)
2013-01-01 to 2008-03-01 FF_LS_METAL (Parameters and models for clay minerals and fcc metals embedded in PCFF and CVFF)
2010-07-01 to 2008-03-01 FF_PHYLLOSILICATES (Parameters and models for clay minerals embedded in PCFF and CVFF)

Please contact hendrik.heinz@uakron.edu for any questions and suggestions.