To run OMC calculation, an additional input file needs to be added: MATCAR Matcar_usage.txt explains the content of MATCAR and shows examples. The matrices shown there are created in VASP output file and listed below the "onsite density matrix" line. The required INCAR Tags to get it are: LDAU = .TRUE. — Turns on the DFT+U machinery. LDAUL = 3 — Sets the orbital quantum number l to 3 for f-electrons; alternatively use 2 for d-electrons, 1 for p-electrons. LDAUPRINT = 1 (or 2) — Controls output verbosity for the onsite occupancy matrix: • LDAUPRINT = 1: Prints the spin-up and spin-down onsite occupancy matrices to the OUTCAR file at each ionic/electronic step (under "onsite density matrix"), alongside eigenvalues and eigenvectors of the total matrix. • LDAUPRINT = 2: Provides even more detailed matrix output. Note: Only for one orbital per atom is HU applied; therefore, for example, for U atoms where there is strong hybridization between 5f and 6d electrons, HU can be applied either to 5f electrons or 6d electrons. Examples of MATCAR for U4C4, rotationally invariant HU applied only to 6d electrons of U: LDAUL = 2 -1: VASP_std: 1 d 30 ### ignored line, beginning atom 1 spin component 1:copied from below onsite density matrix LDAUTYPE = 2 0.0967 -0.0000 -0.0000 0.0000 -0.0000 -0.0000 0.0967 -0.0000 0.0000 0.0000 -0.0000 -0.0000 0.1426 0.0000 0.0006 0.0000 0.0000 0.0000 0.1123 0.0000 -0.0000 0.0000 0.0006 0.0000 0.1433 0.0944 0.0000 -0.0000 0.0000 0.0000 0.0000 0.0944 -0.0000 -0.0000 0.0000 -0.0000 -0.0000 0.1405 0.0000 -0.0008 0.0000 -0.0000 0.0000 0.0825 0.0000 0.0000 0.0000 -0.0008 0.0000 0.1396 ### ignored line, beginning atom 2 spin component 1:copied from below onsite density matrix LDAUTYPE = 2 0.0967 -0.0000 -0.0000 0.0000 -0.0000 -0.0000 0.0967 -0.0000 0.0000 0.0000 -0.0000 -0.0000 0.1426 0.0000 0.0006 0.0000 0.0000 0.0000 0.1123 0.0000 -0.0000 0.0000 0.0006 0.0000 0.1433 0.0944 0.0000 -0.0000 0.0000 0.0000 0.0000 0.0944 -0.0000 -0.0000 0.0000 -0.0000 -0.0000 0.1405 0.0000 -0.0008 0.0000 -0.0000 0.0000 0.0825 0.0000 0.0000 0.0000 -0.0008 0.0000 0.1396 ### ignored line, beginning atom 3 spin component 1:copied from below onsite density matrix LDAUTYPE = 2 0.0967 -0.0000 -0.0000 0.0000 -0.0000 -0.0000 0.0967 -0.0000 0.0000 0.0000 -0.0000 -0.0000 0.1426 0.0000 0.0006 0.0000 0.0000 0.0000 0.1123 0.0000 -0.0000 0.0000 0.0006 0.0000 0.1433 0.0944 0.0000 -0.0000 0.0000 0.0000 0.0000 0.0944 -0.0000 -0.0000 0.0000 -0.0000 -0.0000 0.1405 0.0000 -0.0008 0.0000 -0.0000 0.0000 0.0825 0.0000 0.0000 0.0000 -0.0008 0.0000 0.1396 ### ignored line, beginning atom 4 spin component 1:copied from below onsite density matrix LDAUTYPE = 2 0.0967 -0.0000 -0.0000 0.0000 -0.0000 -0.0000 0.0967 -0.0000 0.0000 0.0000 -0.0000 -0.0000 0.1426 0.0000 0.0006 0.0000 0.0000 0.0000 0.1123 0.0000 -0.0000 0.0000 0.0006 0.0000 0.1433 0.0944 0.0000 -0.0000 0.0000 0.0000 0.0000 0.0944 -0.0000 -0.0000 0.0000 -0.0000 -0.0000 0.1405 0.0000 -0.0008 0.0000 -0.0000 0.0000 0.0825 0.0000 0.0000 0.0000 -0.0008 0.0000 0.1396 VASP_ncl (the same magnetic structure as above with SOC included): 1 d 30 ### ignored line, beginning atom 1 spin component 1:copied from below onsite density matrix LDAUTYPE = 2 0.0973 -0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 -0.0000 0.0000 -0.0000 0.0973 -0.0000 -0.0000 -0.0000 -0.0000 0.0000 0.0000 -0.0000 -0.0000 0.0000 -0.0000 0.1439 0.0000 0.0007 -0.0000 -0.0000 0.0000 0.0000 0.0000 0.0000 -0.0000 0.0000 0.1136 0.0000 0.0000 0.0000 -0.0000 -0.0000 -0.0000 0.0000 -0.0000 0.0007 0.0000 0.1447 -0.0000 0.0000 -0.0000 0.0000 0.0000 0.0954 0.0000 0.0000 0.0000 -0.0000 -0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0954 -0.0000 0.0000 -0.0000 -0.0000 -0.0000 -0.0000 0.0000 0.0000 0.0000 -0.0000 0.1416 0.0000 -0.0008 -0.0000 0.0000 -0.0000 -0.0000 -0.0000 0.0000 0.0000 0.0000 0.0827 0.0000 -0.0000 -0.0000 0.0000 -0.0000 0.0000 -0.0000 -0.0000 -0.0008 0.0000 0.1406 -0.0000 -0.0000 0.0000 -0.0000 0.0000 ### ignored line, beginning atom 2 spin component 1:copied from below onsite density matrix LDAUTYPE = 2 0.0973 -0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 -0.0000 0.0000 -0.0000 0.0973 -0.0000 -0.0000 -0.0000 -0.0000 0.0000 0.0000 -0.0000 -0.0000 0.0000 -0.0000 0.1439 0.0000 0.0007 -0.0000 -0.0000 0.0000 0.0000 0.0000 0.0000 -0.0000 0.0000 0.1136 0.0000 0.0000 0.0000 -0.0000 -0.0000 -0.0000 0.0000 -0.0000 0.0007 0.0000 0.1447 -0.0000 0.0000 -0.0000 0.0000 0.0000 0.0954 0.0000 0.0000 0.0000 -0.0000 -0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0954 -0.0000 0.0000 -0.0000 -0.0000 -0.0000 -0.0000 0.0000 0.0000 0.0000 -0.0000 0.1416 0.0000 -0.0008 -0.0000 0.0000 -0.0000 -0.0000 -0.0000 0.0000 0.0000 0.0000 0.0827 0.0000 -0.0000 -0.0000 0.0000 -0.0000 0.0000 -0.0000 -0.0000 -0.0008 0.0000 0.1406 -0.0000 -0.0000 0.0000 -0.0000 0.0000 ### ignored line, beginning atom 3 spin component 1:copied from below onsite density matrix LDAUTYPE = 2 0.0973 -0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 -0.0000 0.0000 -0.0000 0.0973 -0.0000 -0.0000 -0.0000 -0.0000 0.0000 0.0000 -0.0000 -0.0000 0.0000 -0.0000 0.1439 0.0000 0.0007 -0.0000 -0.0000 0.0000 0.0000 0.0000 0.0000 -0.0000 0.0000 0.1136 0.0000 0.0000 0.0000 -0.0000 -0.0000 -0.0000 0.0000 -0.0000 0.0007 0.0000 0.1447 -0.0000 0.0000 -0.0000 0.0000 0.0000 0.0954 0.0000 0.0000 0.0000 -0.0000 -0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0954 -0.0000 0.0000 -0.0000 -0.0000 -0.0000 -0.0000 0.0000 0.0000 0.0000 -0.0000 0.1416 0.0000 -0.0008 -0.0000 0.0000 -0.0000 -0.0000 -0.0000 0.0000 0.0000 0.0000 0.0827 0.0000 -0.0000 -0.0000 0.0000 -0.0000 0.0000 -0.0000 -0.0000 -0.0008 0.0000 0.1406 -0.0000 -0.0000 0.0000 -0.0000 0.0000 ### ignored line, beginning atom 4 spin component 1:copied from below onsite density matrix LDAUTYPE = 2 0.0973 -0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 -0.0000 0.0000 -0.0000 0.0973 -0.0000 -0.0000 -0.0000 -0.0000 0.0000 0.0000 -0.0000 -0.0000 0.0000 -0.0000 0.1439 0.0000 0.0007 -0.0000 -0.0000 0.0000 0.0000 0.0000 0.0000 -0.0000 0.0000 0.1136 0.0000 0.0000 0.0000 -0.0000 -0.0000 -0.0000 0.0000 -0.0000 0.0007 0.0000 0.1447 -0.0000 0.0000 -0.0000 0.0000 0.0000 0.0954 0.0000 0.0000 0.0000 -0.0000 -0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0954 -0.0000 0.0000 -0.0000 -0.0000 -0.0000 -0.0000 0.0000 0.0000 0.0000 -0.0000 0.1416 0.0000 -0.0008 -0.0000 0.0000 -0.0000 -0.0000 -0.0000 0.0000 0.0000 0.0000 0.0827 0.0000 -0.0000 -0.0000 0.0000 -0.0000 0.0000 -0.0000 -0.0000 -0.0008 0.0000 0.1406 -0.0000 -0.0000 0.0000 -0.0000 0.0000 Examples of MATCAR for U4C4, rotationally invariant HU applied only to 5f electrons of U: LDAUL = 3 -1: 1 f 30 ### ignored line, beginning atom 1 spin component 1:copied from below onsite density matrix LDAUTYPE = 2 0.1019 -0.0000 0.0369 -0.0000 -0.0000 0.0000 0.0000 -0.0000 0.9415 0.0000 -0.0000 -0.0000 -0.0000 0.0000 0.0369 0.0000 0.0829 -0.0000 0.0000 0.0000 -0.0000 -0.0000 -0.0000 -0.0000 0.2833 0.0000 0.0212 0.0000 -0.0000 -0.0000 0.0000 0.0000 0.1163 0.0000 -0.1082 0.0000 -0.0000 0.0000 0.0212 0.0000 0.0490 -0.0000 0.0000 0.0000 -0.0000 0.0000 -0.1082 -0.0000 0.2160 0.0583 0.0000 0.0194 0.0000 -0.0000 0.0000 0.0000 0.0000 0.0246 0.0000 0.0000 0.0000 0.0000 -0.0000 0.0194 0.0000 0.0483 0.0000 -0.0000 -0.0000 0.0000 0.0000 0.0000 0.0000 0.0715 0.0000 -0.0068 -0.0000 -0.0000 0.0000 -0.0000 0.0000 0.0511 -0.0000 -0.0226 0.0000 0.0000 -0.0000 -0.0068 -0.0000 0.0284 0.0000 0.0000 -0.0000 0.0000 -0.0000 -0.0226 0.0000 0.0488 ### ignored line, beginning atom 2 spin component 1:copied from below onsite density matrix LDAUTYPE = 2 0.1019 -0.0000 0.0369 -0.0000 -0.0000 0.0000 0.0000 -0.0000 0.9415 0.0000 -0.0000 -0.0000 -0.0000 0.0000 0.0369 0.0000 0.0829 -0.0000 0.0000 0.0000 -0.0000 -0.0000 -0.0000 -0.0000 0.2833 0.0000 0.0212 0.0000 -0.0000 -0.0000 0.0000 0.0000 0.1163 0.0000 -0.1082 0.0000 -0.0000 0.0000 0.0212 0.0000 0.0490 -0.0000 0.0000 0.0000 -0.0000 0.0000 -0.1082 -0.0000 0.2160 0.0583 0.0000 0.0194 0.0000 -0.0000 0.0000 0.0000 0.0000 0.0246 0.0000 0.0000 0.0000 0.0000 -0.0000 0.0194 0.0000 0.0483 0.0000 -0.0000 -0.0000 0.0000 0.0000 0.0000 0.0000 0.0715 0.0000 -0.0068 -0.0000 -0.0000 0.0000 -0.0000 0.0000 0.0511 -0.0000 -0.0226 0.0000 0.0000 -0.0000 -0.0068 -0.0000 0.0284 0.0000 0.0000 -0.0000 0.0000 -0.0000 -0.0226 0.0000 0.0488 ### ignored line, beginning atom 3 spin component 1:copied from below onsite density matrix LDAUTYPE = 2 0.1019 -0.0000 0.0369 -0.0000 -0.0000 0.0000 0.0000 -0.0000 0.9415 0.0000 -0.0000 -0.0000 -0.0000 0.0000 0.0369 0.0000 0.0829 -0.0000 0.0000 0.0000 -0.0000 -0.0000 -0.0000 -0.0000 0.2833 0.0000 0.0212 0.0000 -0.0000 -0.0000 0.0000 0.0000 0.1163 0.0000 -0.1082 0.0000 -0.0000 0.0000 0.0212 0.0000 0.0490 -0.0000 0.0000 0.0000 -0.0000 0.0000 -0.1082 -0.0000 0.2160 0.0583 0.0000 0.0194 0.0000 -0.0000 0.0000 0.0000 0.0000 0.0246 0.0000 0.0000 0.0000 0.0000 -0.0000 0.0194 0.0000 0.0483 0.0000 -0.0000 -0.0000 0.0000 0.0000 0.0000 0.0000 0.0715 0.0000 -0.0068 -0.0000 -0.0000 0.0000 -0.0000 0.0000 0.0511 -0.0000 -0.0226 0.0000 0.0000 -0.0000 -0.0068 -0.0000 0.0284 0.0000 ### ignored line, beginning atom 4 spin component 1:copied from below onsite density matrix LDAUTYPE = 2 0.1019 -0.0000 0.0369 -0.0000 -0.0000 0.0000 0.0000 -0.0000 0.9415 0.0000 -0.0000 -0.0000 -0.0000 0.0000 0.0369 0.0000 0.0829 -0.0000 0.0000 0.0000 -0.0000 -0.0000 -0.0000 -0.0000 0.2833 0.0000 0.0212 0.0000 -0.0000 -0.0000 0.0000 0.0000 0.1163 0.0000 -0.1082 0.0000 -0.0000 0.0000 0.0212 0.0000 0.0490 -0.0000 0.0000 0.0000 -0.0000 0.0000 -0.1082 -0.0000 0.2160 0.0583 0.0000 0.0194 0.0000 -0.0000 0.0000 0.0000 0.0000 0.0246 0.0000 0.0000 0.0000 0.0000 -0.0000 0.0194 0.0000 0.0483 0.0000 -0.0000 -0.0000 0.0000 0.0000 0.0000 0.0000 0.0715 0.0000 -0.0068 -0.0000 -0.0000 0.0000 -0.0000 0.0000 0.0511 -0.0000 -0.0226 0.0000 0.0000 -0.0000 -0.0068 -0.0000 0.0284 0.0000