Negative Values in E_DENSITY_CUBE Files

Brian Day 22b... at
Thu Jun 28 18:45:23 UTC 2018

I'll have to try and play around with those parameters. That said, do you 
happen to know what the sum of the voxels in these files should be? I 
assume it should be (close to) 1 or (close to) the total number of 
electrons, but with the file attached above I get a value of 46. 34196, 
even though is only a two electron system. Thanks again.


On Wednesday, June 27, 2018 at 3:49:47 PM UTC-4, Matt W wrote:
> 1e-14 seems a small number. I think you can put this down to numerics.
> Maybe decreasing EPS_DEFAULT in the QS section and the STRIDE keyword in 
> the E_DENSITY_CUBE section would give more accurate numbers.
> Matt
> On Wednesday, June 27, 2018 at 8:20:00 PM UTC+1, Brian Day wrote:
>> I'm trying to generate .cube files of the electron density (probability 
>> density). I am using the following lines in my input files (also attached):
>>    &MO_CUBES
>>       NHOMO -1
>>       NLUMO -1
>> I have noticed in the .cube file for the electron density (also 
>> attached), there are a number of values which are negative. Is this due to 
>> a numerical evaluation, or is there another reason for this that anyone is 
>> aware of? The negative values seem to range from -1e-18 to -1e-14, and the 
>> positive values seem to range from 1e-18 to 1e-9. Any help would be greatly 
>> appreciated!
>> Thanks and Regards,
>>      Brian
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