test case breaks for b88 and lyp

[alexm-gc]

I'm probably doing something wrong here, but I get different values when I add your b88 and lyp and compare it against PySCF.

Question Can anyone spot my mistake?

from xcauto.functionals import b88_n_gnn, lyp_n_gnn
import pyscf.dft

print(lyp_n_gnn(1, 1))
print(b88_n_gnn(1, 1))
print( lyp_n_gnn(1, 1) + b88_n_gnn(1,1))
_hyb, fn_facs = pyscf.dft.libxc.parse_xc("1 * B88, 1 * LYP ")
exc = pyscf.dft.libxc._eval_xc(_hyb, fn_facs, np.ones((4, 1)), spin=0, relativity=0, deriv=1, verbose=False)[0]
print(exc)

-0.79051954
[-0.79936469]

I expected the outputs would be the same.

Update: if I change the second argument to 3 it works for some reason. Do you think this is just a coincidence, or is this expected?

print( b88_n_gnn(1,3) + lyp_n_gnn(1,3))
print(pyscf.dft.libxc._eval_xc(_hyb, fn_facs, np.ones((4, 1)), spin=0, relativity=0, deriv=1, verbose=False)[0] 

-0.7993647
[-0.79936469]

---

I managed to get a similar test case to pass for wvn. I imagine my confusion is that wvn only takes one argument, the electron density n, whereas b88 and lyp takes two arguments, n and gnn. I haven't been able to find any documentation for what that is.

import xcauto.functionals 
import pyscf.dft

print( xcauto.functionals.vwn5_n(1) )
_hyb, fn_facs = pyscf.dft.libxc.parse_xc(".2 * HF + .08 * LDA + .72 * B88, .810 * LYP + 1 * VWN")
exc = pyscf.dft.libxc._eval_xc(_hyb, fn_facs[3:4], np.ones((4, 1)), spin=0, relativity=0, deriv=1, verbose=False)[0]
print(exc)

-0.07159259
[-0.07159261]