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

### Description

g_hydorder computes the tetrahedrality order parameters around a given atom. Both angle an distance order parameters are calculated. See P.-L. Chau and A.J. Hardwick, Mol. Phys., 93, (1998), 511-518. for more details.
This application calculates the orderparameter in a 3d-mesh in the box, and with 2 phases in the box gives the user the option to define a 2D interface in time separating the faces by specifying parameters -sgang1 and -sgang2 (It is important to select these judiciously)

### Files

option | filename | type | description
--- | --- | --- | ---
`-f` | `traj.xtc` | Input | Trajectory: xtc trr trj gro g96 pdb cpt
`-n` | `index.ndx` | Input | Index file
`-s` | `topol.tpr` | Input | Run input file: tpr tpb tpa
`-o` | `intf.xpm` | Output, Mult. | X PixMap compatible matrix file
`-or` | `raw.out` | Output, Opt., Mult. | Generic output file
`-Spect` | `intfspect.out` | Output, Opt., Mult. | Generic output file

### 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 | `19` | Set the nicelevel
`-b` | time | `0` | First frame (ps) to read from trajectory
`-e` | time | `0` | Last frame (ps) to read from trajectory
`-dt` | time | `0` | Only use frame when t MOD dt = first time (ps)
`-[no]w` | bool | `no` | View output `.xvg`, `.xpm`, `.eps` and `.pdb` files
`-d` | enum | `z` | Direction of the normal on the membrane: `z`, `x` or `y`
`-bw` | real | `1` | Binwidth of box mesh
`-sgang1` | real | `1` | tetrahedral angle parameter in Phase 1 (bulk)
`-sgang2` | real | `1` | tetrahedral angle parameter in Phase 2 (bulk)
`-tblock` | int | `1` | Number of frames in one time-block average
`-nlevel` | int | `100` | Number of Height levels in 2D - XPixMaps

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