Using pyscf molecular coefficients as input


Is there a possibility to use molecular orbitals from pyscf as input to a QChem calculation?


Yes, this can be done by using the py2qchem module in open-source code MOKIT. For example, let’s perform a simple RHF calculation using PySCF,

from pyscf import gto, scf
from py2qchem import py2qchem

mol = gto.M(atom='''
O  -0.49390246   0.93902438   0.0
H   0.46609754   0.93902438   0.0
H  -0.81435705   1.84396021   0.0

mf = scf.RHF(mol).run()
py2qchem(mf, '')

Then a Q-Chem input file and a directory h2o will be generated. The MOs are held in the directory h2o/. (If the environment variables QCSCRATCH has been defined in your node/computer, the directory h2o will be automatically moved into $QCSCRATCH/; otherwise this directory will be put in the current directory.)

Now you can run

qchem h2o.out h2o

you will see RHF in Q-Chem converges within 2 cycles and the energy cannot be lowered.