The molpro was able to interface and send the info to the MRCC but failed with fatal error in the mrcc execution, please see the section of MRCC from the output file: PROGRAM * MRCC (General Multireference Coupled Cluster) Author: M. Kallay, 2000-2005 *** Initialisation *** Molecular orbitals read from record 1.2 Type=MCSCF/NATURAL (state averaged) Frozen orbitals: 8 ( 4 2 2 0 0 0 0 0) Active orbitals: 15 ( 8 3 3 1 0 0 0 0) Active electrons: 5 Spin quantum number: 0.5 Transformed integrals will be written to file /molpro/mrcc//mrcc_25670/fort.55 Load integrals 2835.8 sec Transform integrals 2839.9 sec Storage for integrals: 4613 Remaining memory: ********* Core energy: -189.14801634 MRCC Input: 3 0 0 0 1 0 0 1 0 0 1 0 1 0 0 7 0 0 0.000 0 16000 ex.lev,nsing,ntrip, rest,method,dens,conver,symm, diag, CS ,spatial, HF, ndoub,nacto,nactv, tol, maxex, sacc, freq, dboc, mem 2 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 MRCC Input end Variable memory released Executing goldstone... Generation of CC equations in terms of H and T... Generation of antisymmetrized Goldstone diagrams... Number of diagrams in T^ 1 equations: 15 Number of diagrams in T^ 2 equations: 37 Number of diagrams in T^ 3 equations: 47 Translation of diagrams to factorized equations... Optimizing intermediate calculation... Number of floating-point operations per iteration step: 0.0000E+00 Probable CPU time per iteration step (hours): 0.00 Required memory (Mbytes): 3.4 Number of intermediates: 13 Number of intermediates to be stored: 11 Length of intermediate file (Mbytes): 0.2 Executing xmrcc... ********************************************************************** CC( 3 ) calculation Allocation of 100.0 Mbytes of memory... Number of spinorbitals: 30 Number of alpha electrons: 3 Number of beta electrons: 1 Spin multiplicity: 2 z-component of spin: 1.0 Spatial symmetry: 1 Convergence criterion: 1.0E-07 Construction of occupation graphs... Number of 0 -fold excitations: 1 Number of 1 -fold excitations: 0 Number of 2 -fold excitations: 0 Number of 3 -fold excitations: 0 Total number of configurations: 1 Calculation of coupling coefficients... Length of intermediate file (Mbytes): 0.2 ====================================================================== Memory requirements /Mbyte/: Minimal Optimal Real*8: 0.0275 0.3889 Integer: 0.2768 Total: 0.3043 0.6657 Executing mrcc... ********************************************************************** CCSDT calculation Allocation of 0.4 Mbytes of memory... Number of spinorbitals: 30 Number of alpha electrons: 3 Number of beta electrons: 1 Spin multiplicity: 2 z-component of spin: 1.0 Spatial symmetry: 1 Convergence criterion: 1.0E-07 Construction of occupation graphs... Number of 0 -fold excitations: 1 Number of 1 -fold excitations: 22 Number of 2 -fold excitations: 210 Number of 3 -fold excitations: 751 Total number of configurations: 984 Fatal error in mrcc. Program will stop. CPU-time for MRCC: 0.0 sec Elapsed-time for MRCC: 0.3 sec Variable memory set to 2000000000 words, buffer space 230000 words