Small fix to uccsd_slow, which is slowly falling behind
Small fix to uccsd_slow, which is slowly falling behind

sunqm/pyscf,gkc1000/pyscf,sunqm/pyscf,sunqm/pyscf,gkc1000/pyscf,gkc1000/pyscf,gkc1000/pyscf,gkc1000/pyscf,sunqm/pyscf