[Pw_forum] Volumetric data units in CUBE file format

[李云海]

Dear Kayahan,

Gaussian cube file uses Hartree's atomic units. That is to say, the  length is in bohr, and the charge is in electron charge.

Thus, the unit for charge density in cube files produced by pp.x is num_electron / bohr^3. 

In the attachment there is a small fortran programm that integrates the scalar field in cube files. Hope it will be of help.

Yunhai Li
Doctoral Student
Department of Physics, Southeast University, P.R.C.

Date: Mon, 10 Nov 2014 16:55:35 -0500
From: saritaskayahan at gmail.com
To: pw_forum at pwscf.org
Subject: [Pw_forum] Volumetric data units in CUBE file format


  

    
  
  
    Dear PWSCF users,
    
    

      
    
    
    I would like to write a script in order to
        manipulate cube files that are output in quantum espresso.
        However, although I find general information about how cube
        files are ordered,(http://paulbourke.net/dataformats/cube/),


        but there is not much information about the unit of electron
        charges on each grid point for volumetric density. Normally,
        when I sum all the charge density values on grid points in a
        loop, multiply with volume and divide by number of grid points I
        should have the total number of electrons in the system, but it
        is not working out for me. I would be happy if someone provide
        some information or documentation which tells how to correctly
        integrate over volumetric density in cube files to find total
        number of electrons. 
    
    
    

      
    
    
    Thanks,
    
    
    Kayahan 
    
      

      

    
    Saritas Kayahan
    
    
    PhD Student
    
    
    MIT
    
    
    Grossman Group
    
    
    Office: 13-4069
    
    
    Office: +1-617-258-8741
    
    
    Email: kayahan at mit.edu
  


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