Hello,

I’m running into some problems with x2c. The 1-norm is very big and the scf result also depends on the reference wavefunction. Each run time the numbers can be different as well. I’m using decontracted 6-31g* here, which is not designed for relativistic calculations, but SARC basis set (uncontracted) for U atom also has the same problem. I imagine this has to do with the linear dependency problem or/and unprotected inversion LAPACK, but how should I fix it? Thanks!

Here’s an example input:

molecule h2o {

Se

H 1 R

H 1 R 2 A

R = 2.0

A = 104.5

units bohr

}

set {

basis 6-31G*-decon

basis_relativistic 6-31g*-decon

scf_type pk

}

set relativistic x2c

en1, wfn1 = energy(‘scf’, return_wfn=True)

set relativistic no

en2, wfn2 = energy(‘scf’, return_wfn=True, reference_wfn=wfn1)

set relativistic x2c

en3, wfn3 = energy(‘scf’, return_wfn=True, reference_wfn=wfn2)

en4, wfn4 = energy(‘scf’, return_wfn=True, reference_wfn=wfn3)

Output:

(en1) The 1-norm of |H_X2C - H_Dirac| is: 41862.990477155596

(en3) The 1-norm of |H_X2C - H_Dirac| is: 41863.183105109230

(en4) The 1-norm of |H_X2C - H_Dirac| is: 41868.473475888735

en1 = -84575.5564468204102013

en2 = -2400.4387878319948868

en3 = -84575.6301333945448278

en4 = -84575.4272162587294588