Converting chemical shielding tensors from LCHIMAG calculations

[carlosbornes]

Hello,

I'm doing some LCHIMAG calculations with VASP and I noticed something strange. I have the following symmetric magnetic shielding tensor

275.016064, 8.323574, -0.296549
6.229964, 272.642428, -1.488598
-1.049309, -2.379348, 272.128976

The G0 contribution is

-5.198851, 0.004894, 0.000606
0.008268, -5.184956, 0.009264
0.001568, 0.009761, -5.196157

and the core contribution

-766.8301203

If I do the calculation myself by adding the G0 tensor to the symmetric
tensor and then the core contribution to the diagonal values and calculate
the isotropic chemical shift, span and skew I get the following values
-498.7610, 15.2678, -0.2515 while VASP gives me -499.2860, 15.2754, -0.2513

Am I doing something wrong? How does VASP go about considering/removing the
contributions?

Best,
Carlos

[alexey.tal]

Dear Carlos,

Could you please provide all relevant input and output files for your calculation according to the forum guidelines?

[carlosbornes]

Here are the files

[alexey.tal]

You need to add "Core contribution to magnetic susceptibility" as well. It is provided in OUTCAR: -125.32 10^-6 cm^3/mole or
-0.5247454 ppm.

[carlosbornes]

Hi Alexey,

I see, I was not aware that this needed to be added also. By the way, how did you go from the -125.32 10^-6 cm^3/mole to
-0.5247454 ppm? I don't see this last value in the OUTCAR

[alexey.tal]

The conversion factor can be found in linear_response_NMR.F:

Code: Select all

CHI_FACT= 3._q/8._q/PI*LATT_CUR%OMEGA*6.022142E23/1.E24

The volume in your OUTCAR is 3320.6197, so -125.32/CHI_FACT = -0.525