Commands for the relax application

Metadata

This document was edited May 25th 2010 by Mike Tyka. This application in mini was created and documented by Mike Tyka, et al.

The "relax" application in Rosetta carries out the task of simple structural refinement of fullatom Rosetta models. It can also read Centroid models, in which case it will convert the model into a fullatom model and pack the sidechains. Relax does not carry out any extensive refinement and only searches the local conformational space neighbourhood.

Input

Relax takes as input one or more structures in silent or PDB format. All JD2 options apply (see JD2 Documentation ofr more details)

Output

Relax outputs one or more structures in silent or PDB format. All JD2 output options apply (see JD2 Documentation ofr more details) As always -nstruct regulates the number of outputs per input structure.

Command lines

Sample command*

relax.linuxgccrelease -database ~/minirosetta_database -in:file:s input.pdb -in:file:fullatom -native 1a19.pdb -out:file:silent default.out -relax:quick

Relax can take all general file IO options common to all Rosetta pplication writen with JD2: (see JD2 documentation for details)

   -database                 Path to minirosetta databases
   -in:file:s                Input pdb file(s)  
   -in:file:silent           Input silent file
   -in:file:fullatom         Read as fullatom input structure
   -score:weights            Supply a different weights file (default is score12)
   -score:patch              Supply a different patch file (default is score12)
   -run:shuffle              Use shuffle mode, treat structures in random order
   -nstruct                  Make how many decoys per input structure ?

Options specific to relax

   Simple Options:
   -relax:fast               Do a simple, small cycle number (5)  fast relax (DEFAULT)
   -relax:thorough           Do a preset, large cycle number (15) fast relax
  
   Advanced Options
   -relax:script <file>      Do custom script relax (you can supply a custom script file)

   Deprecated Modes (don't use)
   -relax:classic            Do an old old deprecated "classic" relax mode (slow and poor performance)

Example

The example above with input files can be found in demo/relax/ Just execute the run.sh script.

Results

Relax returns full-atom relaxed structures. Relax is a genral purpose protcol and used in many different applications where fullatom structures are required at the end. In most cases relax is the last step in a larger protocol and the lowest energy structures are of interest to the user.

Description of algorithm

For virtually all situations it should be sufficient to use either -relax:quick or -relax:thorough and not worry about all the options.

The fast relax modes work by running many sidechain repack and minimisation cycles ramping up and down the repulsive weight of the forcefield. This sort of "pulses" the structure in successive collapse and expansion phases which "wiggles" the atoms into a low energy state. No explicit moves are done (this was found not to be useful as most moves are rejected and dont help lowering the nergy). Not that despite that fact, the structure can change up to 2-3 A from the starting conformation during the minimisation cycles.

FastRelax is a more modern version of the initial fast relax algotihm which is more flexible and allows definitino of a specific script of relax events (how exactly the repack and minimisation cycles are interlaced and what paramters they should take). This is defined in a script file. An example script file looks like this:

repeat 15 
ramp_repack_min 0.02  0.01
ramp_repack_min 0.250 0.01
ramp_repack_min 0.550 0.01
ramp_repack_min 1     0.00001
accept_to_best
endrepeat

The above command chain would do 15 repeats of a ramp-profile of 0.02, 0.25, 0.550 and 1.0 of the repulsive weight. At each step a repack is followed by a minimisation with a tolerance of 0.01,0.01,0.01 and 0.00001 respectively. Over all the weight would pulse in this order 0.02, 0.25, 0.550, 1.0, 0.02, 0.25, 0.550, 1.0, 0.02, 0.25, 0.550, 1.0, 0.02, 0.25, 0.550, 1.0 ... The lowest energy structure encountered at the full weight is reported back at the end.

NOTE: It should virtually never be necessary to mess with the preset script or parameters! Dont touch unless you know what you're doing!

Relax Script Format description:

Valid commands include:

repeat <loopcount>

starts a section to be repeated <loopcount> times - end the block with "endrepeat". Nested loop are NOT supported.

endrepeat

is the end marker of a loop. loops may *NOT* be nested! (this is not a programming language. well it is. but a very simple one.)

accept_to_best

compares the energy of the current pose and the best_pose and replaces the best pose with the current pose if it's energy is lower.

load_best

Load the best_pose into the current working pose, replacing it.

load_start

Load the starting pose into the current working pose, replacing it.

Sets the best_pose to the current pose whatever the energy of the current pose.

dump <number>

Dumps a pdbfile called dump_<number>.pdb

scale:<scoretype> <scale>

Scales the scoretype's default value by whatever the scale number is. For ex, scale:fa_rep 0.1 will take the original fa_rep weight and set it to 0.1 * original weight.

weight:<scoretype> <weight>

Sets the weight of the scoretype to whatever the weight number is. ALSO CHANGES DEFAULT WEIGHT. This is so in weight, scale, scale routines the scale will be using the user-defined weight, which seems to make more sense. For ex, weight:fa_rep 0.2 will take set fa_rep to 0.2

show_weights

Outputs the current weights. If a parameter is not outputted, then its weight is 0. Most useful when redirecting stdout to a file, and only one input structure.

coord_cst_weight <scale>

Sets the coordinate_constraint weight to <scale>*start_weight. This is used when using the commandline options -constrain_relax_to_native_coords and -constrain_relax_to_start_coords.

repack

Triggers a full repack

min <tolerance>

Triggers a dfp minimization with a given tolernace (0.001 is a decent value)

ramp_repack_min <scale:fa_rep> <min_tolerance> [ <coord_cst_weight = 0.0> ]

Causes a typical ramp, then repack then minimize cycle - i.e. bascially combines the three commands scale:fa_rep, repack and min (and possible coord_cst_weight)

These two scripts are equivalent:

scale:fa_rep 0.5
repack
min 0.001

and

ramp_repack_min 0.5 0.001

batch_shave <keep_proportion>

Valid for batchrelax only - ignored in normal FastRelax In Batchrelax it will remove the worst structures from the current pool and leave only <keep_proportion>. I.e. the command

batch_shave 0.75

Will remove the worst 75% of structures from the current working pool.

exit

will quit with immediate effect

A typical FastRelax script is: (thi sin fact is the default command script)

repeat 5 
ramp_repack_min 0.02  0.01     1.0
ramp_repack_min 0.250 0.01     0.5
ramp_repack_min 0.550 0.01     0.0
ramp_repack_min 1     0.00001  0.0
accept_to_best
endrepeat

For developers only:

For development and optimization, these options are also present. These are provided on a as-is basis with no guarantee of functionality or purpose. Use with care.

  
  Options specific to the fast relax mode (normally you don't need to meddle with these!)
		
   -relax:script                Script file
   -relax:script_max_accept     Limit number of best accepts, default = 10000000