| ## tpbconv Main Table of Contents | VERSION 4.6 Sat 19 Jan 2013

### Description

tpbconv can edit run input files in four ways.

1. by modifying the number of steps in a run input file with options `-extend`, `-until` or `-nsteps` (nsteps=-1 means unlimited number of steps)

2. (OBSOLETE) by creating a run input file for a continuation run when your simulation has crashed due to e.g. a full disk, or by making a continuation run input file. This option is obsolete, since mdrun now writes and reads checkpoint files. Note that a frame with coordinates and velocities is needed. When pressure and/or Nose-Hoover temperature coupling is used an energy file can be supplied to get an exact continuation of the original run.

3. by creating a `.tpx` file for a subset of your original tpx file, which is useful when you want to remove the solvent from your `.tpx` file, or when you want to make e.g. a pure Cα `.tpx` file. Note that you may need to use `-nsteps -1` (or similar) to get this to work. WARNING: this `.tpx` file is not fully functional.

4. by setting the charges of a specified group to zero. This is useful when doing free energy estimates using the LIE (Linear Interaction Energy) method.

### Files

option | filename | type | description
--- | --- | --- | ---
`-s` | `topol.tpr` | Input | Run input file: tpr tpb tpa
`-f` | `traj.trr` | Input, Opt. | Full precision trajectory: trr trj cpt
`-e` | `ener.edr` | Input, Opt. | Energy file
`-n` | `index.ndx` | Input, Opt. | Index file
`-o` | `tpxout.tpr` | Output | Run input file: tpr tpb tpa

### Other options

option | type | default | description
--- | --- | --- | ---
`-[no]h` | bool | `no` | Print help info and quit
`-[no]version` | bool | `no` | Print version info and quit
`-nice` | int | `0` | Set the nicelevel
`-extend` | real | `0` | Extend runtime by this amount (ps)
`-until` | real | `0` | Extend runtime until this ending time (ps)
`-nsteps` | int | `0` | Change the number of steps
`-time` | real | `-1` | Continue from frame at this time (ps) instead of the last frame
`-[no]zeroq` | bool | `no` | Set the charges of a group (from the index) to zero
`-[no]vel` | bool | `yes` | Require velocities from trajectory
`-[no]cont` | bool | `yes` | For exact continuation, the constraints should not be applied before the first step
`-init_fep_state` | int | `0` | fep state to initialize from

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