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Ctrl section is introduced using the

`%ctrl`

directive.
%ctrl npoints 4096 deltar 0.05 mix_param 0.5 conv_crit 1e-9 max_iter 5000 max_dsqn 1e+2 use_nr nr_max_iter 50 nr_mix_param 0.0 nr_conv_crit 1e-1 graph #nograph grxmin 0.0 grxmax 12.0 %end

In the ctrl section, the statements/keywords described in the following text are valid. The list is sorted alphabetically.

conv_crit *conv_crit_value*

Convergence criterion for the iteration procedure – the DSQN value is compared to this value. If DSQN is smaller, then the convergence was achieved.

default: 1e-9

allowed values: real, conv_crit > 0

deltar *deltar_value*

Discretization step size. Please note that for potentials involving discontinuities (e.g., hard spheres), this value should be chosen to be consistent with the position of the discontinuities (discontinuity should be located at integer multiple of the step size) in order to avoid inaccuracies.

default: 0.05 Å

allowed values: any, greater than 0

graph / nograph

Switch specifying whether the graphical output should be done during the iteration procedure. If enabled, pyOZ displays the interaction potentials, direct and indirect (Gamma) correlation functions in real and Fourier space, and the resulting pair correlation functions. This feature is experimental and doesn’t seem to work reliably (the display is a bit flakey).

default: nograph

allowed values: none

grxmin *grxmin_value* / grxmax *grxmax_value*

Range of the x-axis when plotting is performed, otherwise ignored. If incorrect values are entered, the defaults are used.

default: 0.0 Å / 10 Å

allowed values: any real

max_dsqn *max_dsqn_value*

Maximum value of DSQN in the iteration cycle. If DSQN is larger than this number, the calculation is probably diverging and will be terminated.

default: 100

allowed values: float > 0

max_iter *max_iter_value*

Maximum number of iterations to be performed.

default: 1000

allowed values: integer > 0

mix_param *mix_param_value*

Mixing parameter α for the direct iteration scheme. Defines the proportion of new and old Gamma functions during mixing. The value of 1 means that the new Gamma will be used directly for new step (no mixing with function from previous step).

default: 0.4

allowed values: 0 < mix_param ≤ 1

nograph

See graph / nograph.

npoints *npoints value*

Number of points to be used for discretization of pair potentials and correlation functions.

default: 4096

allowed values: any power of 2

nr_conv_crit *nr_conv_crit_value*

Relative convergence criterion for the NR/CG iteration procedure. In order to avoid unnecessary iterations in the beginning of the procedure, where the linear approximation is not so appropriate, the NR subcycle is iterated until a certain fraction (given by this keyword) of the DSQN of the main cycle is achieved.

default: 1e-1

allowed values: real, conv_crit > 0

nr_max_iter *nr_max_iter_value*

Maximum number of iterations to be performed in each Newton-Raphson subcycle. If convergence is not reached within this number of steps, classical Picard mixing is performed instead.

default: 50

allowed values: integer > 0

nr_mix_param *nr_mix_param_value*

Mixing parameter for the NR/CG scheme. Defines the fraction of the B that is to be used as X in order to start the iteration.

default: 0.0

allowed values: 0 < nr_mix_param ≤ 1

nr_noconv_incr

If set, the calculated increment will be used even if NR procedure fails. If not set, the program falls back to the standard Picard procedure for this iteration.

default: false

allowed values: none

use_nr

Switch specifying whether the improved Newton-Raphson/conjugate gradients iteration technique should be used (currently supported only for HNC closure).

default: false

allowed values: none

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