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<body class='hmmessage'><div dir='ltr'><br>Dear Kayahan,<br><br>Gaussian cube file uses Hartree's atomic units. That is to say, the length is in bohr, and the charge is in electron charge.<br><br>Thus, the unit for charge density in cube files produced by pp.x is num_electron / bohr^3. <br><br>In the attachment there is a small fortran programm that integrates the scalar field in cube files. Hope it will be of help.<br><br>Yunhai Li<br>Doctoral Student<br>Department of Physics, Southeast University, P.R.C.<br><br><div><hr id="stopSpelling">Date: Mon, 10 Nov 2014 16:55:35 -0500<br>From: saritaskayahan@gmail.com<br>To: pw_forum@pwscf.org<br>Subject: [Pw_forum] Volumetric data units in CUBE file format<br><br>
<small>Dear PWSCF users,
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<div><small>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,(<a href="http://paulbourke.net/dataformats/cube/" target="_blank">http://paulbourke.net/dataformats/cube/</a>),
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. </small></div>
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<div><small>Thanks,</small></div>
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<div><small>Kayahan </small></div>
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<div><small>Saritas Kayahan</small></div>
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<div><small>PhD Student</small></div>
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<div><small>MIT</small></div>
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<div><small>Grossman Group</small></div>
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<div><small>Office: 13-4069</small></div>
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<div><small>Office: +1-617-258-8741</small></div>
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<div><small>Email: <a href="mailto:kayahan@mit.edu">kayahan@mit.edu</a></small></div>
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