quantum-espresso/TDDFPT/Doc/INPUT_Spectrum.xml

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<input_description distribution="Quantum Espresso" package="turboTDDFPT" program="turbo_spectrum.x" >
   <toc>
   </toc>
   <intro>
    Input data format: { } = optional, [ ] = it depends.

All quantities whose dimensions are not explicitly specified are in
RYDBERG ATOMIC UNITS

BEWARE: TABS, DOS &lt;CR&gt;&lt;LF&gt; CHARACTERS ARE POTENTIAL SOURCES OF TROUBLE

Comment lines in namelists can be introduced by a &quot;!&quot;, exactly as in
fortran code. Comments lines in ``cards&apos;&apos; can be introduced by
either a &quot;!&quot; or a &quot;#&quot; character in the first position of a line.

Structure of the input data:
===============================================================================

&amp;lr_input
  ...
/
   </intro>
   <namelist name="lr_input" >
      <label> This namelist is always needed !
      </label>
      <var name="prefix" type="CHARACTER" >
         <default> &apos;pwscf&apos;
         </default>
         <info>
Sets the prefix for generated and read files. The files
generated by the ground state pw.x run should have this
same prefix.
         </info>
      </var>
      <var name="outdir" type="CHARACTER" >
         <default> &apos;./&apos;
         </default>
         <info>
The directory that contains the run critical files, which
include the files generated by ground state pw.x run.
         </info>
      </var>
      <var name="verbosity" type="INTEGER" >
         <default> 1
         </default>
         <info>
This integer variable controls the amount of information
written to standard output.
         </info>
      </var>
      <var name="itermax0" type="INTEGER" >
         <default> 500
         </default>
         <info>
Number of Lanczos coefficients to be read from the file.
         </info>
      </var>
      <var name="itermax" type="INTEGER" >
         <default> 500
         </default>
         <info>
The total number of Lanczos coefficients that will be
considered in the calculation of the polarizability/absorption
coefficient. If itermax &gt; itermax0, the Lanczos coefficients
in between itermax0+1 and itermax will be extrapolated.
         </info>
      </var>
      <var name="extrapolation" type="CHARACTER" >
         <default> &apos;no&apos;
         </default>
         <info>
    Sets the extrapolation scheme. &apos;osc&apos;= biconstant extrapolation,
&apos;constant&apos;=constant extrapolation and &apos;no&apos;=no extrapolation.
         </info>
      </var>
      <var name="epsil" type="REAL" >
         <default> 0.02
         </default>
         <info>
The broadening/damping term (in Rydberg units).
         </info>
      </var>
      <var name="units" type="INTEGER" >
         <default> 0
         </default>
         <info>
    The unit system used for the output and the start, end and increment
input parameters.

0 = Rydbergs, 1 = Electron volts and 2 = Nanometres per electron volts.
         </info>
      </var>
      <var name="start" type="REAL" >
         <default> 0.0
         </default>
         <info>
  The polarizability and the absorption coefficient are computed
starting from this value. In units set by the units variable.
         </info>
      </var>
      <var name="end" type="REAL" >
         <default> 2.5
         </default>
         <info>
  The polarizability and the absorption coefficient are computed
up to this value. In units set by the units variable.
         </info>
      </var>
      <var name="increment" type="REAL" >
         <default> 0.001
         </default>
         <info>
  Incremental step used to define the mesh between start and end.
In units set by the units variable.
         </info>
      </var>
      <var name="ipol" type="INTEGER" >
         <default> 1
         </default>
         <info>
An integer variable that determines which element of the
dynamical polarizability will be computed:
1 -&gt; alpha_xx(omega), 2 -&gt; alpha_yy(omega), and
3 -&gt; alpha_zz(omega). When set to 4, three Lanczos chains
are sequentially performed and the full polarizability
tensor and the absorption coefficient are computed.
         </info>
      </var>
      <var name="eels" type="LOGICAL" >
         <default> .false.
         </default>
         <info>
Must be set to .true. for EELS. EELS-specific operations
will be performed.
         </info>
      </var>
      <var name="td" type="CHARACTER" >
         <default> &apos;lanczos&apos;
         </default>
         <info>
When set to &apos;lanczos&apos;, a calculation of the spectrum is
performed using the Lanczos coefficients.
When set to &apos;davidson&apos; or &apos;david&apos;, a calculation of the
spectrum is performed using the eigenvalues computed
using the Davidson algorithm. See the variable &apos;eign_file&apos;.
         </info>
      </var>
      <var name="eign_file" type="CHARACTER" >
         <default> &apos;pwscf.eigen&apos;
         </default>
         <info>
The name of the file produced by the turbo_davidson.x code,
in which are written the eigenvalues.
         </info>
      </var>
   </namelist>
</input_description>