The .md file

The .md file is provided as a single source for the all the dynamical data produced by a CASTEP calculation. In all cases, data is printed in Hartree atomic units. Fortran formating data will be given here for all entries in this file for those who wish to import it into their own analysis codes.

Note that unlike the .castep file, the .md file from a previous calculation with the same seedname will be overwritten, unless the new calculation is a continuation of the original.

Header

At the top of every .md file a header is written as below. The total length is four lines including blanks. The comments written are taken from the cell/parameter files.

 BEGIN header
  
 This is 8 atom cubic Si cell  
 END header

This is followed by a blank line. There is a single space at the start of each non-blank line. This header is written once only.

Time and Energy Data

The next entry will be the data for the first MD step. This begins with the current time on the first line, followed by the Total, Hamiltonian, and Kinetic energy on the second line with the label <-- E.

               0.00000000E+000
              -3.18206146E+001     -3.18108683E+001      9.74270683E-003  <-- E

Formatting:

format(12x,es18.8e3)
format(9x,3(3x,es18.8e3),'  <-- E')

Thermodynamic Data

The current temperature is then printed with the label <-- T. If the output is from a variable cell calculation, or calculate_stress has been explicitly set to true, the pressure is also printed with the label <-- P.

                9.27876841E-04                                            <-- T
                5.85402338E-06                                            <-- P

Formatting:

format(12x,es18.8,T73,   '  <-- T')
format(12x,es18.8,T73,   '  <-- P')

Cell Data

For all calculations, the current matrix of cell vectors is printed with the label <-- h. Each row gives the three Cartesian components of one of the cell vectors.

               1.01599045E+001      0.00000000E+000      0.00000000E+000  <-- h
               1.29430839E-017      1.01599045E+001      0.00000000E+000  <-- h
               1.29430839E-017      1.29430839E-017      1.01599045E+001  <-- h

Formatting:

format(9x,3(3x,es18.8e3),'  <-- h')
format(9x,3(3x,es18.8e3),'  <-- h')
format(9x,3(3x,es18.8e3),'  <-- h')

The remaining cell data is only printed for variable cell calculations, regardless of the value of calculate_stress. First the velocity of each cell vector is printed with the label <-- hv.

               2.80052926E-008     -1.42751448E-007     -1.35787248E-007  <-- hv
              -1.42751448E-007      2.76907508E-008     -1.44694219E-007  <-- hv
              -1.35787248E-007     -1.44694219E-007      2.71532850E-008  <-- hv

Formatting:

format(9x,3(3x,es18.8e3),'  <-- hv')
format(9x,3(3x,es18.8e3),'  <-- hv')
format(9x,3(3x,es18.8e3),'  <-- hv')

The full pressure tensor (including kinetic contributions) is then printed with the label <-- S in a similar fashion.

              -6.21684372E-006      3.03062374E-005      3.23291890E-005  <-- S
               3.03062374E-005     -6.06171719E-006      3.31426773E-005  <-- S
               3.23291890E-005      3.31426773E-005     -5.79666096E-006  <-- S

Formatting:

format(9x,3(3x,es18.8e3),'  <-- S')
format(9x,3(3x,es18.8e3),'  <-- S')
format(9x,3(3x,es18.8e3),'  <-- S')

Ionic Data

Data on the current ionic configuration is then printed. Atoms are identified by their chemical symbol in the first column, and number of the atom within the species in the second.

First the position vectors of all ions are printed with the label <-- R.

 Si     1      1.04834750E-002      1.15560090E-002      7.82230990E-003  <-- R
 Si     2     -3.20400394E-003      5.07172565E+000      5.10986361E+000  <-- R
 Si     3      5.07271954E+000      5.11656710E+000     -2.45225140E-003  <-- R
 Si     4      5.10789066E+000     -2.63240242E-002      5.09753015E+000  <-- R
 Si     5      7.57309188E+000      2.52845762E+000      7.57612741E+000  <-- R
 Si     6      2.55271297E+000      2.54057876E+000      2.53924276E+000  <-- R
 Si     7      2.53422324E+000      7.64091983E+000      7.62428191E+000  <-- R
 Si     8      7.63167143E+000      7.59610368E+000      2.52717191E+000  <-- R

Formatting (for each atom):

format(1x,a3,1x,i4,3(3x,es18.8e3),'  <-- R')

Velocities are then printed in a similar fashion.

 Si     1      5.77278549E-005      7.23673746E-005      4.30349159E-005  <-- V
 Si     2     -1.72415752E-005     -5.23270551E-005      1.75385181E-004  <-- V
 Si     3     -4.17085102E-005      2.14539848E-004     -1.78769096E-005  <-- V
 Si     4      1.58756714E-004     -1.60916056E-004      9.49147966E-005  <-- V
 Si     5     -2.70431102E-004     -7.18757382E-005     -2.43440176E-004  <-- V
 Si     6      7.51663795E-005      8.70332331E-008     -8.82271461E-006  <-- V
 Si     7     -4.19898677E-005      1.31687892E-004      3.60873179E-005  <-- V
 Si     8      7.97201068E-005     -1.33563298E-004     -7.92824105E-005  <-- V

Formatting (for each atom):

format(1x,a3,1x,i4,3(3x,es18.8e3),'  <-- V')

Finally forces are printed.

Si     1     -4.23569381E-003      2.52214252E-003     -2.46018145E-003  <-- F
Si     2      3.06338418E-003     -2.16206923E-003     -5.29928454E-003  <-- F
Si     3      7.37259995E-004     -4.73479365E-003     -2.20030945E-003  <-- F
Si     4     -6.89050954E-003     -2.25153379E-003     -8.37626756E-003  <-- F
Si     5      4.53551291E-003      3.34757083E-003      1.02791157E-002  <-- F
Si     6      2.06737343E-003      2.05175887E-003      2.70990363E-003  <-- F
Si     7     -1.41457164E-003     -9.15433604E-004      1.54850432E-003  <-- F
Si     8      2.13724448E-003      2.14235805E-003      3.79851935E-003  <-- F

Formatting (for each atom):

format(1x,a3,1x,i4,3(3x,es18.8e3),'  <-- F')

A blank line is then printed, and the process repeats with the data from the next time-step.