From molecular characteristics to material properties
J-OCTA can be used to simulate...
- - Molecular dynamics simulation (engine name: COGNAC, VSOP)
- - Interface/phase separation simulation (engine name: SUSHI, COGNAC-DPD)
- - Rheology simulation (engine name: VSOP-DPD, PASTA, NAPLES)
- - Multi-phase structure simulation (engine name: MUFFIN)
The modeling tools provided in J-OCTA for each engine are introduced here. Interfaces with other software, the QSPR function for the simplified calculation of polymer properties, and inter-scaling coupling functions - including zooming and reverse mapping - are available.
Molecular dynamics simulation (COGNAC, VSOP)
Evaluate and estimate the static and dynamic properties of the material at the atomic/molecule level.
- All-atom modeling (1)
- Write a chemical formula directly on the screen for quick and easy 3D molecular structure creation. Create a polymer by combining the resulting monomer models. The system can construct a block copolymer or a random copolymer and control the tacticity. Importing files in various file formats including PDB and CIF is supported. By specifying reaction points in an atomic element, the chemical reactions during the molecular dynamics calculation and the crosslinking can be defined. See also "Reaction modeling."
- All-atom modeling (2)
- For the force field parameters, AMBER, GAFF, DREIDING, OPLS-AA, L-OPLS, UFF and CLAY are available for use. Direct Force Field (Team Force Field) is also available to obtain the force field parameters. What is "Direct Force Field"?
- All-atom modeling (3)
- By directly performing quantum chemical calculations including Gaussian, Firefly/ PC-GAMESS a point charge can be obtained.
- Force field parameter adjustment
- This feature can adjust the bond potential in molecules and the LJ potential parameters for inorganic/organic interfaces, in accordance with the structure resulting from a quantum calculation (DFT or MO) and the potential energy. Automatic allocation of parameters is also available, and users can adjust the parameters with discussing comparisons of the given potential curve and the quantum calculation result.
- Coarse Grained modeling
- In the Coarse Grained modeling, an atomic assembly is treated as a unit (grained unit). Coarse grained models can calculate a large scale phenomenon that persists over a long period. The software possesses a function for estimating the coarse-grained potential based on the all-atom model. Case Study: Evaluation of Coarse Grained Potential
- System modeling
- Construct a system by allocating the molecules that are generated by using an all-atom model or a coarse grained model. For a full atomic model, the system can be an amorphous structure or a crystal structure of the inorganic material. By merging these two systems, the organic-inorganic interface structure can be constructed. For a coarse grained model, the system can be constructed by creating filler using Kremer-Grest or DPD, or, by inserting filler into a polymer.
- Reaction modeling
- By specifying two molecules as reaction points in an atomic, users can setup various items such as parameters for the chemical reaction calculation using MD, a post-reaction structure, force field parameters, and the charge.
* VSOP is necessary for a reaction calculation using MD.
Case Study: Simulation of Crosslinked Epoxy Resin. Case Study: Properties of Cross-Linked Phenolic Resins.
- External engine
- J-OCTA also possesses a function to convert the data to LAMMPS and GROMAC, and can run these molecular dynamics engines directly on J-OCTA. What is LAMMPS?
- Parallel molecular dynamics engine: VSOP
- VSOP (Parallel molecular dynamics engine) improves the calculation speed dramatically and enables large calculations that are not possible without parallelization.
- Post analysis
- In addition to the simulation function implemented in OCTA engine, J-OCTA can simulate the free volume, the primitive path, and the spherical model filling in a specified region. It is possible to export a density distribution for FEM simulation, in the format of a tetra mesh, a voxel mesh, or an STL.
*...VSOP is a high-speed parallel molecular dynamics engine that is co-developed by the JSOL corporation and Japan Atomic Energy Agency (JAEA).
Interface, phase separation simulation (SUSHI, COGNAC-DPD)
Estimate the phase separation structure and the interface geometry of materials with various molecular structure and block copolymers by using the mean field method (SUSHI) and the dissipative particle dynamics method (COGNAC-DPD).
- Estimate calculation of the interaction parameters
- Estimate the interaction parameter (χ parameter). (1) Estimate the SP value (solubility parameter) by using the group contribution method, QSPR, or molecular dynamics to obtain the χ parameter. (2) Obtain the χ parameter based on the contact energy between the Coarse Grained segments and the coordination number. (3) Back calculate the χ parameter based on the experimental phase diagram. Case study: Estimation of χ Parameters from Phase Diagrams
- Generate a mesh from the phase separation structure
- Convert the phase separation structure to an FEM mesh. Generate a mesh along the interface and export the volume fraction distribution into a finer mesh. (For the latter function, please refer to the description for MUFFIN as well.)
- KRI-NIWA method
- The KRI-NIWA method is a new group contribution method developed by KRI, Inc. that can estimate SP values more precisely than the traditional group contribution method. Estimate χ parameters based on the estimated SP values.
- Initial concentration distribution
- By combining multiple geometries (box, sphere, and cylinder), a concentration distribution or an obstacle domain can be created.
Rheology simulation (VSOP-DPD, PASTA, NAPLES)
Estimate the rheology property of the melted polymer or of the polymer considering the effects of the molar weight distribution and branch structure by using the slip link model (PASTA).
- Entanglement polymer model
- Build models considering the branch structure and crosslinking of the polymer and the molar weight distribution by using parameters such as the entanglement molecular weight. Shear and elongation flow are possible flow fields.
- Entanglement polymer model calculation with DPD
- The DPD calculation function implemented in VSOP can consider the entanglement effect of the polymer chain with slip spring. It allows users to evaluate material properties such as viscoelasticity.
Multi-phase material simulation (MUFFIN)
Perform simulations of the elastic materials using the finite element method with the imported phase separation structure that is obtained by, e.g., the mean field method.
- Import the phase separation structure
- Import the phase separation structure obtained by the mean field method or DPD as an elastic modulus distribution on the FEM mesh. Estimate the stress distribution and the energy distribution on the interface and the mean elastic modulus that are obtained by the elastic simulation using MUFFIN.
- Generate an FEM mesh along the interface by allocating simple spheres inside the rectangular domain. The result can be used to simulate the virtual phase separation structure and the composite materials.
- Multi-layer fluid simulation
- Build models to perform a simulation with a micro-fluid that contains multiple polymers and/or electrolytes. These models are applicable to the calculation of thin film formation with phase separation (e.g., solvent evaporation) and other related phenomena.
- External engine
- LS-DYNA link : The phase separation structure in voxel mesh which is output from SUSHI (SCF), DPD or CGMD can be used to run LS-DYNA structural analysis (uniaxial tensile, biaxial tensile, and shear deformation) and thermal analysis. The material can be elastic, elastoplastic, hyperelastic, or viscoelastic. * This function will be released in next version. Refer LS-DYNA
- Representative volume element for composite materials
- COGNAC can create a structure (Representative Volume Element(RVE)) of a rectangle region which is highly filled (over 50 vol%) with particles, fibers, and discoid shaped fillers. The resulting structure can be transferred to Digimat-FE and be output as an STL file and a voxel mesh. These files can be used for FEM simulation for composite materials. Refer Digimat-FE
First-Principles Calculation (SIESTA)
First-Principles (FP) simulations make use the basic laws of quantum mechanics to give an insight of material properties such as electronic, mechanical, magnetic properties without making assumptions in empirical models or using fitting parameters. DFT (Density Functional Theory) calculation is one of the most popular methods in the FP simulation field. Current computational power enables to calculate properties of several hundreds to thousands of atoms with DFT.
SIESTA is a registered trade-mark of SIMUNE.
SIMUNE Website >>
- SIESTA interfacial energy tool
- This tool gives an easy way to evaluate interaction energies between a surface and a molecule with SIESTA. It is possible to estimate surface adsorption energies from the interaction energy curve. Based on the interaction energies, force field parameters for molecular dynamics simulation can be estimated. Case Study: Example of Calculation with SIESTA
Multi-scale coupling function
Determine the molecular construction of polymers by using a large scale simulation result. The large scale result employs multi-scale approaches and enables the generation of a relaxation molecular construction that is complicated when general molecular dynamics is used.
- Create the molecular dynamics structure based on the volume fraction distribution (phase separation structure) of each component obtained with the mean field method (SUSHI). This function is especially useful to create the molecular construction around the interface.
- Reverse mapping function
- Create the all-atom molecular dynamics structure by using the molecular construction obtained by the coarse-grained molecular dynamics. The resulting structure can be used to create the initial structure of the all-atom model and the evaluation of the coarse grained model (to be compared with the experiment).
Quantitative Structure-Property Relationships (QSPR)
Estimate a range of the material properties of the polymer by the input molecular construction. This function outputs a list of material properties including the density, thermal expansion coefficient, glass transition point temperature, Poisson's ratio, and dielectric constant. This is a powerful tool to support the molecular design of an organic polymer.
Estimated physical properties
- - van der Waals volume
- - Molar volume
- - Density
- - Volume thermal expansion coefficient, linear thermal expansion coefficient
- - Heat capacity at constant pressure
- - Amount of change in the heat capacity near the glass transition point
- - Cohesive energy, solubility parameter, χ parameter
- - Glass transition temperature
- - Surface tension, interfacial tension
- - Refractive index, molar refractive index, dielectric constant
- - Lorentz and Lorenz molar polarization, effective dipole moment
- - Dissipation factor
- - Molar diamagnetic susceptibility
- - Poisson's ratio, bulk modulus, shear elastic modulus, Young’s modulus
- - Entanglement molecular weight
- - Brittle fracture stress, yield stress
- - Property ratio
- - Zero-shear viscosity
- - Thermal conductivity, thermal diffusivity
- - Permeability (oxygen, nitrogen, carbon dioxide)
- Link and run engines
- Direct link to OCTA engine as well as the external engines allows users to perform a local run (on Windows) or a remote run (on Linux) . Interface access to the job management system is also available. A parametric calculation for given simulation conditions is possible.
- 3D drawing
- 3D drawing feature supports a small-scale molecular drawing for editing a model as well as a large-scale model drawing. It is possible to draw a model which contains millions or tens of millions of particles.
- Simulation procedure can be saved as a scenario which is created in an easy-to-understand flowchart style. By registering a scenario, users can repeat a common simulation procedure with different materials. Scenario is useful to share a procedure in your team as well.
|CPU||Multi-core CPU (recommended)|
|Memory||4 GB or more (recommended) / 2 GB (required)|
|Display resolution||1024 X 768 or more (recommended)|
|Graphics card||OpenGL-compatible graphics card (nVidia or ATI is recommended)|
|Display colors||65536 colors or more (recommended)|
- * J-OCTA Student Edition does not support the operating systems listed below:
- ・Windows 7（32bit）
|CPU||Multi-core CPU (recommended)|
|Memory||2 GB or more (recommended)|