====== Processing of rovibrational line lists (DAT2GR) ======

The DAT2GR program is used to process and to generate plots from rovibrational infrared and Raman line lists generated by the RCI and RVCI programs that are part of the VSCF and VCI progam.

===== The DAT2GR program (DAT2GR) =====

''DAT2GR'',//options//

The ''DAT2GR'' program allows for the processing of rovibrational line lists (IR and Raman) to modify data, apply line-broadening and temperature effects or generate plots. The file containing the line list must be generated before by the RCI or RVCI methods which are part of the ''VSCF'' or ''VCI'' programs. ''DAT2GR'' does not require any ''XSURF'' or ''VSCF'' calculations prior to its call, but requests at least a Hartree-Fock calculation, which is always needed in Molpro.\\
The following //options// are available:

  * **''DUMP''=//filename//** This keyword defines the name of the output file to be generated.
  * **''EINC''=//value//** (= 0.1 Default, in cm$^{-1}$) Output spectrum is calculated on a grid with width EINC; i.e. determines the resolution of the x-Axis in the final spectrum.
  * **''EMAX''=//value//** (= 5000 Default, in cm$^{-1}$) This option specifies the maximum energy of the spectral range to be considered.
  * **''EMIN''=//value//** (= 0 Default, in cm$^{-1}$) This option specifies the minimum energy of the spectral range to be considered.
  * **''EXTERN''=//filename//** This keyword is mandatory and requests the input filename (rovibrational line list) as generated from the R(V)CI programs.
  * **''GAMMA''=//value//** Mandatory keyword, if presure broadening is used. Describes the width of the Lorentz profil in cm$^{-1}$. The width can be determined by the equation: $\gamma = \frac{p A}{\pi c}  \sqrt{\frac{2}{k_B T m}} $, with pressure $p$, cross section of the molecule $A$, speed of light $c$, Boltzmann constant $k_B$, temperature $T$ and Molecular mass $m$.
  * **''METHOD''=//string//** (=’INT’ Default) This option controls the method of data handling, e.g. whether the data should be modified/filtered or (re-)calculated. Options are ’MOD’ (modify/filter exisiting line list), ’INT’ (calculate T-dependent intensities from exisiting intensities at $T=0$ K), ’INT_TM’ (calculate Raman intensities from transition moments $R_0$ and $R_2$ in the input line list).
  * **''PINC''=//value//** (= 0.1 atm Default, in ''PUNIT'') Pressure increment to be considered. Only needed for Voigt profile.
  * **''PLIST''=//string//** (off Default) List of pressures to be considered, e.g. ’1.0,1.1,1.2’. Combinable with other pressure-keywords. Only needed for Voigt profile.
  * **''PMAX''=//value//** (= 1.0 atm Default, in ''PUNIT'') Maximum pressure to be considered. Only needed for Voigt profile.
  * **''PMIN''=//value//** (= 1.0 atm Default, in ''PUNIT'') Minimum pressure to be considered. Only needed for Voigt profile.
  * **''PRINT''=//n//** (=0 (off) Default) ''PRINT=2'' enables additional printout.
  * **''PROFILE''=//string//** (=’GAUSSIAN’ Default) This option controls the line shape to be used for accounting of line-broadening or in the case of data modification/filtering (''%%METHOD=’MOD’%%'') what's to be done. ''%%PROFILE=’Lines’%%'' will return a line list again. ''%%PROFILE=’Lorentz’%%'' sets the line shape to be Lorentzians, ''%%PROFILE=’Gauss’%%'' will use Gaussians. ''%%PROFILE=’Voigt’%%'' specifies a line shape from numerical convolution of Gaussians and Lorentzians, which is numerically expensive. The combined half-widths $\sigma$ for the Gaussian and $\gamma$ for the Lorentzian line shape are calculated from the temperature and pressure using a physical description. ''%%PROFILE=’Gaussian’%%'' specifies a simple Gaussian line shape with half-width ''SIGMA''. For ''%%METHOD=’MOD’%%'' the options are ''%%PROFILE=’SORT’%%'' to sort the data by the column specified with the keyword ''SORT'' or ''%%PROFILE=’SYMSEL’%%'' to apply symmetry selection rules.
  * **''PUNIT''=//string//** (=’atm’ Default) Pressure unit. without any broadening. 
  * **''RAMAN_FAC(n)''=//value//** Set the prefactors for the isotropic and anisotropic Raman transition moments for the calculation of Raman intensities manually. $n=0$ will set the value for $R_0$, $n=2$ the one for $R_2$.
  * **''RAMAN_LFREQ''=//value//** (=680 Default, in nm) Raman exciting radiation (laser) frequency.
  * **''RAMAN_POLANG''=//value//** (=90 Default) Raman polarisation angle defining the prefactors mixing the isotropic and anisotropic Raman transition moments for the calculation of Raman intensities.
  * **''SIGMA''=//value//** (= 1.0 Default, in cm$^{-1}$) Mandatory keyword, if Doppler broadening is used. Describes the width of the Gaussian profile in cm$^{-1}$. The width can be determined by the equation: $\sigma = \frac{1}{c}  \sqrt{\frac{8 k_B T ln(2)}{m}} $, with speed of light $c$, Boltzmann constant $k_B$, temperature $T$ and Molecular mass $m$ and natural logarithm.
  * **''SORT''=//n//** (=12 (frequencies) Default) ''PRINT=2'' enables additional printout.
  * **''TINC''=//value//** (= 100 Default, in K) Temperature increment to be considered. Only needed for Voigt profile.
  * **''TLIST''=//string//** (off Default, in K) List of temperatures to be considered, e.g. ’200,250,300’. Combinable with other temperature-keywords. Only needed for Voigt profile.
  * **''TMAX''=//value//** (=0 (off) Default, in K) Maximum temperature to be considered. Setting only ''TMIN'' will set ''TMAX'' to the same value. Only needed for Voigt profile.
  * **''TMIN''=//value//** (=0 (off) Default, in K) Minimum temperature to be considered. Setting only ''TMAX'' will set ''TMIN'' to the same value.Only needed for Voigt profile.
  * **''TYPE''=//string//** (=’IR’ Default) This option controls the type of line list to be handled, but it will be set according to the input line list type anyway. Options are ’IR’ or ’Raman’.

The following example generates a rovibrational IR spectrum for the spectral range between 900 and 1100 cm$^{-1}$ for the given temperature of 300 K from the line list provided in the file ''H2CS_IR_VCI_J3.dat'' and dumps the output to ''H2CS_IR_VCI_J3_graph.dat''.\\

<code>
!options: --logfile-scratch
memory,50,m
mass,iso

geometry={
   S
   C,S,rcs
   H1,C,rch,S,ahcs
   H2,C,rch,S,ahcs,H1,180
}

rcs = 1.2 ang
rch = 1.0 ang
ahcs = 120 degree

basis=vdz
hf
dat2gr, extern='H2CS_IR_VCI_J3.dat', Emin=900, Emax=1100, Einc=1d-1
dat2gr, type='IR', profile='Voigt', dump='H2CS_IR_VCI_J3_graph.dat', TList='300', print=2
</code>