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Pseudopotential file(s)

Besides the inp.mod and start.inp/inp.ini files considered so far the fhi98md requires supply of pseudopotentials  for each of the nsp  atomic species listed in start.inp. Pseudopotential file(s) must be provided in the working directory according to the following naming convention:

species #   pseudopotential filename
1 $\rightarrow$ fort.11
2 $\rightarrow$ fort.12
     
nsp $\rightarrow$ fort.1nsp

In practice, the pseudopotential data are copied to the working space by the same shell script (batch file under Windows) which runs the fhi98md program.



#! /bin/csh -xvf
....
############## set directories ######################


set PSEUDO = [pseudopotentials directory]
set WORK = [working directory]
.....


########### change to the working space #############


cd $WORK


#### move pseudopotentials to the working space ####


cp $PSEUDO/ga:lda:ham.cpi fort.11
cp $PSEUDO/as:lda:ham.cpi fort.12
.....


######################################################
# run fhi98md #
######################################################
./fhi98md
.....


Pseudopotentials are read in during the initialization when control is delivered to the init routine2.1. The tpsmesh  parameter in start.inp allows the user to instruct the fhi98md about the format of the pseudopotential data file(s):

Parameter Type/Value  
tpsmesh  logical form of the pseudopotential
  .true. tabulated on logarithmic mesh
  .false. set up from parametrized form

Ionic pseudopotentials  in the format  accepted by the fhi98md program can be generated and tested by means of the fhi98pp package . The latter provides the psgen tool  which produces as chief output a pseudopotential data file name.cpi formated as shown in Fig. 2.2 (for more details the user is referred to the article [26]).

  
Figure 2.2: Format of the pseudopotential file name.cpi as generated by the psgen tool.
\begin{figure}\epsfig{file=psp.eps,width=14cm}\end{figure}

When setting up the start.inp file one should ensure that the values of the zv  and lmax  parameters match those of the $Z_{\rm ion}$ and $l_{\max}+1$ fields, respectively, in the pseudopotential files for each species. The fhi98md program stops if ${\it zv} \neq Z_{\rm ion}$ or if not enough angular momentum components have been provided, i.e. $l_{\max}+1 < {\it lmax}$

Parameter Type  
lmax integer highest angular momentum of the pseudopotential ( 1 $\rightarrow s$, 2 $\rightarrow p$, 3 $\rightarrow d$)
l_loc integer angular momentum of the local pseudo potential ( l_loc $\leq$ lmax)
Special care should be paid also to the l_loc  parameter(s) in file start.inp: it must be set to the same value used in generating the pseudopotential. If for any reason the user would like to change l_loc, then a new pseudopotential has to be constructed according to the new l_loc value.

Sometimes an explicit account of the core-valence nonlinearity of the exchange-correlation functional is required, for instance in studies involving alkali metal atoms [26]. In this case the psgen tool appends at the end of the name.cpi file a data block containing the partial core density, Fig. 2.2. The fhi98md program automatically recognizes the use of such a pseudopotential and the proper information record is written to fort.6  during the initialization.

Note also that pseudopotentials should be generated and used within the same exchange-correlation scheme.


next up previous contents index
Next: Input files for advanced Up: Description of the program Previous: The input file inp.ini
Matthias Wittenberg
1999-08-06