1. The difference charge density can be calculated and made readable in a suitable format by post-processing with input file BN.dcd.in as follows:

############################BN.dcd.in##############################

&inputpp

prefix='BN'

outdir='./tmp'

filplot='BN.rho'

plot_num=9

/

&plot

nfile=1

filepp(1)='BN.rho'

weight(1)=1.0

iflag=3

output_format=3

e1(1)= 2, e1(2)=0, e1(3)=0

e2(1)= 0, e2(2)=2, e2(3)=0

e3(1)= 0, e3(2)=0, e3(3)=3.982131

x0(1)=-1.0, x0(2)=-1.0, x0(3)=0.0

nx=50, ny=50, nz=50

fileout='BN.dcd.xsf'

/

###################################################################

2. Launch the post-processing with the following command:

$pp.x<BN.dcd.in>BN.dcd.out

3. The difference charge density can be visualized with XCrySDen or VESTA by opening with the file BN.dcd.xsf.