ABP:Controls

Navigation: Documentation / Methods / Adaptive Biasing Potential Method / ABP:Controls

---

The behaviour of the Adaptive Biasing Potential (ABP) method is controlled by the setup provided in the [abp] section. This section belongs to the {PMFLIB} group. The ABP method implemented in PMFLib calculates the mollified free energy from a smoothed population of selected collective variables. The obtained free-energy surface is therefore not the exact free energy and has to be corrected by deconvolution. This post-processing is performed by the abp-energy utility.

[abp]

Key	Default value	Type	Description
fmode	0	integer	The mode of the Adaptive Biasing Potential method: 0 - the method is disabled 1 - the method is enabled If the method is enabled, at least one collective variable has to be provided for ABP sampling.
fhbias	3.0	real	The bias height used to control the strength of the adaptive biasing potential. The value is provided in the currently selected energy unit.
feimode	1	integer	The extrapolation/interpolation mode used for the ABP force evaluation: 1 - linear ramp mode
fhramp	10	integer	The ramp size used in the linear ramp mode. The ramp reduces the ABP force in poorly sampled regions and gradually switches it on as the local mollified population increases.
fsample	5000	integer	Every fsample MD steps, the accumulated ABP data will be printed to the ABP output file. The name of the output file is provided in the [files] section. If fsample is zero, the regular output is disabled.
frestart	off	logical	Disable/Enable restarting the ABP simulation from the previous run. The name of the restart file is provided in the [files] section.
frstupdate	5000	integer	Every frstupdate MD steps, the ABP restart file will be written. If frstupdate is zero, periodic writing of the restart file is disabled.
ftrjsample	0	integer	Every ftrjsample MD steps, the ABP accumulator is written to the ABP trajectory file. This file can be used to analyse the evolution of the mollified free-energy estimate. If ftrjsample is zero, the trajectory output is disabled.

[abp-walker]

Key	Default value	Type	Description
fserverkey		string	The key file used to connect the ABP walker to an MWA server in the multiple-walkers setup. If the key is not provided, the multiple-walkers ABP mode is disabled. This option is available only if PMFLib was compiled with network support.
fserverupdate	500	integer	Every fserverupdate MD steps, the ABP walker exchanges accumulated data with the ABP server.
fabortonmwaerr	on	logical	Disable/Enable abortion of the simulation if communication with the MWA server fails. If this option is disabled, the simulation can continue even after a multiple-walkers communication error.
fconrepeats	0	integer	The maximum number of repeated attempts to reconnect to the MWA server after a communication failure. If the number of failed attempts exceeds fconrepeats, the action depends on fabortonmwaerr: if it is enabled, the simulation is aborted; otherwise, the multiple-walkers ABP mode is disabled, and the simulation continues without server communication.