Output Summary File

When the self-consistent field problem is solved for a specific set of parameters, in response to an ITERATE command in the parameter file, PSCF outputs an output summary file named “out”, in addition to files containing the final omega and rho fields. The format of this summary file is similar to that of the parameter file, except that it contains some additional information about thermodynamic properties and computational details near the end of the file.

Example

Here is an example of an output summary file produced by a simulation of the BCC of a diblock copolymer melt. The majority of the file, up until the FINISH line, has the same format as a parameter file, so that this part of the file can be used as the basis of a parameter file for a new simulation. The THERMO and STATISTICS sections appear after the FINISH line, and contain additional information about, respectively, thermodynamic properties of the converged solution and about computational aspeces of the simulation.

 format  1  0

MONOMERS
N_monomer
                   2
kuhn
    1.0000000000E+00    1.0000000000E+00

CHAINS
N_chain
                   1
N_block
                   2
block_monomer
                   1                   2
block_length
    2.0000000000E-01    8.0000000000E-01

COMPOSITION
ensemble
                   0
phi_chain
    1.0000000000E+00

INTERACTION
interaction_type
               'chi'
chi
    2.4000000000E+01

UNIT_CELL
dim
                   3
crystal_system
             'cubic'
N_cell_param
                   1
cell_param
    1.8447588337E+00

DISCRETIZATION
ngrid
                  24                  24                  24
chain_step
    1.0000000000E-02

BASIS
group_name
          'I m -3 m'

ITERATE
input_filename
          'in.omega'
output_prefix
              'out/'
max_itr
                  20
error_max
    1.0000000000E-08
domain
                   T
itr_algo
                'NR'
N_cut
                  95

FINISH

THERMO
f_Helmholtz
    2.7451703490E+00
f_homo
    2.8400000000E+00
pressure
    3.7365224085E+00
mu_chain
    6.4816927575E+00
stress
   -6.0758291562E-11

STATISTICS
N_star
                 231
final_error
    6.0758291562E-09
iterations
                  10
basis_time
    5.6800000000E+00
scf_time
    1.3674400000E+02

THERMO Section

The thermodynamics section contains final values for the following thermodynamic properties of the converged solution. All quantities that involve energy (i.e., f_Helmholtz and mu) are output in units in which thermal energy is set to kT=1. The pressure is output in units in which kT=1 and in which the monomer reference volume is =1.

Variable	Description
f_Helmholtz	Helmholtz free energy per monomer / kT
f_homo	f_Helhmoltz of a hypothetical homogeneous mixture
pressure	Macroscopic pressure x monomer volume / kT
mu_chain	chemical potential / kT, for each polymer species
mu_solvent	chemical potential / kT, for each solvent species
phi_chain	total volume fraction for each polymer species
phi_solvent	total volume fraction for each solvent species
stress	derivatives of free energy per monomer / kT

Values of mu_chain and mu_solvent appear in this section if and only if the calculation was carried out in canonical ensemble (ensemble == 0), in which case the corresponding species volume fractions are given as input parameters in the COMPOSITION section. Conversely, values of phi_chain and phi_solvent vectors appear in this output section only if the calculation was carried out in grand-canonical ensemble (ensemble == 1), in which case the corresponding chemical potential values are given as inputs in the COMPOSITION section.

Units: The Helmholtz free energy f_Helmholtz is given in this section is a dimensionless free energy per monomer, normalized by kT. In the simple case of a single component block copolymer melt, the free energy per chain is then given by the product of f_Helmholtz and the overall chain length (sum of the block lengths given in the parameter file). Similarly, the reported pressure is a dimensionless value obtained by multiplying the pressure by the monomer reference volume and then dividing by kT. Values of mu_chain and (if present) mu_solvent are instead free energies per molecule, normalized by kT.

In a system with more than one chain and/or solvent component, a value would be given for the chemical potential of each species, with one value per line. The mu_solvent (in canonical ensemble) or phi_solvent (in grand-canonical ensemble) array appears only if the parameter file has a SOLVENTS input section with one or more solvent species.

Each element of the array of values of “stress” is the derivative of the dimensionless free energy per monomer f_Helmholtz with respect to one of the unit cell parameters. The number of elements is thus equal to N_cell_param, the number of parameters required to describe the unit cell. All components of this array should be very close to zero at the end of a computation with a flexible unit cell (domain == T).

Please refer to the Appendix: Self-Consistent Field Theory for documentaiton of the mathematical expressions used to compute free energies and other physical properties.

STATISTICS Section

The statistics section contains information about the size N_star of the basis used to approximate the rho and omega fields, the number of iterations required, the final error, and the amount of time taken for different parts of the computation. Times are given in seconds.