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Features of PSCF programs are listed below, grouped so as to indicate the computational methods and programs to which they apply:
Features for both SCFT and PS-FTS (all programs):
- Ability to treat mixtures containing any number of block polymer, homopolymer, and solvent molecular species
- Ability to treat acyclic branched block polymers, as well as linear polymers
- Ability to use canonical, grand-canonical or mixed statistical ensembles
- Thorough user and developer documentation provided via an integrated web manual
- Well documented source code written in object-oriented C++
- Example input files for many types of calculation
- Python tools for data analysis and file processing
Features for SCFT (all programs):
- Efficient Anderson-mixing SCFT iteration algorithms
- Efficient "parameter sweeps": SCFT calculations for a sequence of states along a path in parameter space, with continuation of solutions
All remaining features listed below are specific to the pscf_rpc and pscf_rpg programs, which provide identical features using different hardware. Both of these programs are designed for systems with periodic boundary conditions, and can both perform either SCFT or PS-FTS calculations. In SCFT, the periodic unit cell is often chosen so as to represent a single crystallographic unit cell of a periodic structure. In PS-FTS calculations, the periodic computational unit cell usually represents a larger region.
Features for SCFT or PS-FTS on periodic systems (pscf_rpc and pscf_rpg):
- Choice of continuous thread or discrete bead-spring models of polymer chains
- High accuracy pseudo-spectral solution of the modified diffusion equation for the continuous thread model
- Periodic unit cells with 1, 2 or 3 dimensional periodicity
- Unit cells with all possible 2D and 3D Bravais lattice systems (i.e., cubic, orthorhombic, monoclinic, etc.)
- A companion matlab package (Polymer Visual for visualization of periodic c-fields or w-fields
Features for SCFT on periodic systems (pscf_rpc and pscf_rpg):
- Efficient algorithms to find optimal unit cell parameters in SCFT
- Imposition of any user-selected space-group symmetry on SCFT solutions
- Built-in database of symmetry operations for all 230 3D space groups and 17 2D plane groups
- Inhomogeneous density constraint (a "mask")
- Inhomogeneous selective external fields
- Thin polymer films (implemented using a mask and external fields)
Features for PS-FTS with periodic boundary conditions (pscf_rpc and pscf_rpg):
- Brownian dynamics (BD) and Monte Carlo (MC) sampling algorithms
- BD algorithms: Leimkuhler-Matthews, predictor-corrector and explicit Euler step algorithms
- MC algorithms: real-space and "smart"/force-bias MC moves
- Efficient algorithms for adjusting the pressure field so as to find a partial saddle-point (i.e., to impose incompressibility)
- Tools to calculate free energy differences by thermodynamic integration, including the Einstein-crystal method
- Parameter "ramps" in which one or more parameters change continuously during a simulation
- Analysis tools to compute quantities of interest, including the structure factor, order parameters used to identify phase transitions, and averages of derivatives of the Hamiltonian that are needed for thermodynamic integration calculations
- Statistical analysis can be performed either during a simulation or by postprocessing of field trajectory files that are created during a simulation
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