!butene
symmetry,nosym ! Embedding is not implemented with symmetry

{gthresh,grid=1e-12,orbital=1e-8,coeff=1e-7}

geometry={
C1,,          0.835432384 ,   0.049538050 ,  -1.305177530
C2,,         -0.187431703 ,  -1.125601622 ,   1.070665830
C3,,         -0.143380420 ,   0.687719249 ,   3.341106035
H1,,         -2.118667450 ,  -1.789600571 ,   0.735591607
H2,,          0.942690000 ,  -2.802115823 ,   1.537268881
H3,,         -0.860542916 ,  -0.240216354 ,   5.042940132
H4,,         -1.309266799 ,   2.354788168 ,   2.978399494
H5,,          1.778149207 ,   1.339614495 ,   3.742333311
C4,,         -0.440429873 ,   0.344384131 ,  -3.450328416
H6,,          2.782544497 ,   0.715697009 ,  -1.206788342
H7,,         -0.434433198 ,  -1.089606640 ,  -4.914726597
H8,,         -1.545390643 ,   2.035286250 ,  -3.818951212
} !Geometry is in Bohr

basis=def2-svp

! Step 1: Perform DFT on full system.
! Level shift added for improved convergence for this system.
!  The system is a butene where the double bond is twisted by 90 degrees.
{rks,b-lyp,shifta=-0.3}

! Step 2: Define the procedure that will be used for the embedded calculation.
!         Here, we define a standard MRCI calculation.
proc embedded_mrci
    ! Step 2a: Generate initial orbitals for MCSCF.
    {rhf}

    ! Step 2b: Perform MCSCF calculation.
    ! When performing an embedded MCSCF calculation, always specify the active space.
    {mcscf;
    config,csf;
    OCC,9;
    closed,7;
    frozen,2;}

    ! Step 2c: Add dynamic correlation
    {mrci}
endproc

! Step 3: Call embedding code and specify the atoms corresponding to the twisted double bond. Provide the procedure for the embedded calcuation.
{embed,atoms=[C1,C4,H6,H7,H8],highproc=embedded_mrci}