@@ -429,6 +429,13 @@ target_link_libraries(eccejobmaster PRIVATE
 add_executable(ecce-localdata src/apps/localdata/ecce-localdata.C)
 target_include_directories(ecce-localdata PRIVATE ${XercesC_INCLUDE_DIRS})
 target_link_libraries(ecce-localdata PRIVATE ecceutil ${XercesC_LIBRARIES})
+# An MO's atomic-orbital composition from a calculation folder (#161).
+# Installed as bin/mocomp; its wrapper is ecce-mocomp like every CLI app's.
+add_executable(mocomp src/apps/mocomp/mocomp.C)
+target_include_directories(mocomp PRIVATE ${XercesC_INCLUDE_DIRS})
+target_link_libraries(mocomp PRIVATE
+  eccedsi eccedav eccecipc eccefaces eccexml eccetdat eccedsi eccexml ecceutil
+  ${XercesC_LIBRARIES})
 # flock(1) for the session scripts where util-linux is absent (macOS).
 add_executable(ecce-flock src/apps/flock/ecce-flock.c)
 # The server half of "ecce -admin" on a -remote client (SiteRequest).
@@ -847,7 +854,6 @@ export ECCE_REALUSERHOME=\${ECCE_REALUSERHOME:-$HOME}
 exec \"$ECCE_HOME/bin/ecce-site-admin\" \"$@\"
 ")
 install(PROGRAMS ${_sadm_wrapper} DESTINATION ${ECCE_WRAPPER_DESTINATION} COMPONENT client)
-
 foreach(_ds start stop status adduser)
   set(_ds_wrapper ${CMAKE_BINARY_DIR}/wrappers/ecce-dataserver-${_ds})
   file(WRITE ${_ds_wrapper}
@@ -895,7 +901,7 @@ set(ECCE_GUI_APPS
   mddynamics mdenergy mdoptimize mdprepare msgdialog metadyn organizer
   passdialog hostkeydialog pertable polyed solvate builder vizthumbnail)
 set(ECCE_CLI_APPS
-  load_tgbs ecmd eccejobmaster eccejobstore ecce-localdata ecce-flock ecce-site-admin
+  load_tgbs ecmd eccejobmaster eccejobstore ecce-localdata ecce-flock ecce-site-admin mocomp
   autosym getfrag genmol genmollat cleansym symops)
 
 install(TARGETS ${ECCE_GUI_APPS} ${ECCE_CLI_APPS} RUNTIME DESTINATION bin
@@ -2011,6 +2017,14 @@ if(PYTHON3_EXECUTABLE)
                    $<TARGET_FILE:importmeta>)
   set_tests_properties(importmeta PROPERTIES TIMEOUT 300 ENVIRONMENT
     "ECCE_HOME=${CMAKE_SOURCE_DIR};ECCE_REALUSER=fragreaders")
+  # tests/mocomp: ecce-mocomp's Mulliken and c^2 compositions against
+  # checked-in Multiwfn numbers (#161); re-derives them where Multiwfn is
+  # installed (MULTIWFN, or Multiwfn_noGUI on PATH).
+  add_test(NAME mocomp
+           COMMAND ${PYTHON3_EXECUTABLE}
+                   ${CMAKE_CURRENT_SOURCE_DIR}/tests/mocomp/run_tests.py
+                   ${CMAKE_BINARY_DIR})
+  set_tests_properties(mocomp PROPERTIES TIMEOUT 300)
   add_test(NAME fragreaders
            COMMAND fragreaders ${CMAKE_CURRENT_SOURCE_DIR}/tests/fragreaders/data)
   file(MAKE_DIRECTORY ${CMAKE_BINARY_DIR}/fragreaders-home)
 
@@ -105,7 +105,9 @@ $wrote
 3pd
 4-31g
 5d
+6-21g
 6-31++g
+6-31++g*
 6-31++g**
 6-31+g*
 6-311++g
@@ -141,6 +143,7 @@ activeelectrons
 activeorbitals
 activities\
 additional
+ahlrichs
 ai.gauss09
 ai.gauss09\n
 ai.gauss16
@@ -246,6 +249,7 @@ cartesian
 cas
 casscf
 category
+cbsb7
 cc
 cc-pv5z
 cc-pv6z
@@ -255,6 +259,9 @@ cc-pvtz
 cc.convergenceenergy.value
 cc.convergenceiterations
 cd-demon\n
+cep-121g
+cep-31g
+cep-4g
 cerium
 cesium
 charge
@@ -311,14 +318,21 @@ d6d
 d6h
 d8h
 d95
+d95**
 d95v
+def2-qzv
 def2-qzvp
+def2-sv
 def2-svp
+def2-tzv
 def2-tzvp
 def2-tzvpp
+def2qzv
 def2qzvp
+def2sv
 def2svp
 def2svpp
+def2tzv
 def2tzvp
 def2tzvpp
 density
@@ -331,6 +345,7 @@ dftxcfitting
 dictionary
 dielectric
 difference
+differs
 diis
 direct
 directly
@@ -345,6 +360,7 @@ dunning
 dunning-hay
 dysprosium
 dz
+dzp
 e
 ecce
 ecce_ai_debug
@@ -355,6 +371,8 @@ empiricaldispersion
 end\n
 energy
 enonly
+epr-ii
+epr-iii
 erbium
 error
 error:
@@ -495,6 +513,7 @@ job
 kcis
 krypton
 lanl2dz
+lanl2mb
 lanthanum
 lawrencium
 lc-whpbe
@@ -649,6 +668,7 @@ promethium
 protactinium
 pseudo
 punch
+pvdz
 pw6b95
 pw6b95d3
 pw91
@@ -709,6 +729,7 @@ scf.levelshiftsize
 scrf
 scripts
 sd
+sdd
 sdq
 se
 seaborgium
@@ -741,6 +762,7 @@ stepsize
 sto-2g
 sto-3g
 sto-3g*
+sto-6g
 strontium
 sub
 subroutine
@@ -750,6 +772,7 @@ sulfur
 super
 superfine
 sv
+svp
 svwn
 svwn5
 symmetry
@@ -794,9 +817,12 @@ true
 ts
 tungsten
 type:
+tzv
+tzvp
 u
 uccd
 udft
+ugbs
 uhf
 ultra
 ultrafine
@@ -816,6 +842,7 @@ user
 useroutecard
 usesymmetry
 vanadium
+vdz
 version\n
 very
 verytight
 
@@ -84,8 +84,10 @@ $wrote
 2pd
 2}\n
 3-21g
+3-21gsp
 3df
 3pd
+4-22gsp
 6-31++g**
 6-31+g*
 6-311++g
@@ -115,6 +117,7 @@ $wrote
 a
 activities
 activities.\n
+ahlrichs
 ai.orca
 ai.orca:
 also
@@ -125,12 +128,29 @@ are
 argument
 as
 atoms!\n
+aug-cc-pcvdz
+aug-cc-pcvqz
+aug-cc-pcvtz
 aug-cc-pv5z
 aug-cc-pv6z
 aug-cc-pvdz
 aug-cc-pvqz
 aug-cc-pvtz
+aug-cc-pwcvdz
+aug-cc-pwcvqz
+aug-cc-pwcvtz
+aug-pc-0
 aug-pc-1
+aug-pc-2
+aug-pc-3
+aug-pcseg-0
+aug-pcseg-1
+aug-pcseg-2
+aug-pcseg-3
+aug-pcsseg-0
+aug-pcsseg-1
+aug-pcsseg-2
+aug-pcsseg-3
 b2gp-plyp
 b2plyp
 b3lyp
@@ -164,12 +184,20 @@ cam-b3lyp
 cannot
 category
 cc
+cc-pcvdz
+cc-pcvqz
+cc-pcvtz
 cc-pv5z
 cc-pv6z
 cc-pvdz
 cc-pvdz-dk
 cc-pvqz
+cc-pvqz-dk
 cc-pvtz
+cc-pvtz-dk
+cc-pwcvdz
+cc-pwcvqz
+cc-pwcvtz
 ccsd
 charge
 charges
@@ -214,13 +242,15 @@ descriptive
 details
 dft
 dictionary
+differs
 directly
 dlpno-ccsd
 dlpno-mp2
 dropped
 dsd-blyp
 dsd-pbep86
 dump
+ecce
 ecce_ai_debug
 ecp
 end\n
@@ -272,10 +302,13 @@ h
 has
 help\n
 hf
+huzinaga
 hybrid
 i
 idx
 if
+iglo-ii
+iglo-iii
 ih
 implausible
 in
@@ -306,6 +339,8 @@ maxiter
 mb/core
 memorysize
 method
+midi
+mini
 missing
 model
 molecular
@@ -340,13 +375,26 @@ p
 pbe
 pbe0
 pc-1
+pc-2
+pc-3
+pc-4
+pcseg-1
+pcseg-2
+pcseg-3
+pcseg-4
+pcsseg-0
+pcsseg-1
+pcsseg-2
+pcsseg-3
+pcsseg-4
 pertab.pl
 pick
 polar
 polarization
 potential
 print[p_mos]
 print[p_orben]
+pvdz
 pwpb95
 quadrupole
 r
@@ -385,6 +433,8 @@ substitution
 such
 supported.\n
 supported:
+sv
+svp
 symbol
 symmetry
 t
@@ -409,7 +459,9 @@ tpssh
 treating
 true\n
 turn
+tzv
 udft
+ugbs
 uhf
 uks
 ump2
@@ -420,6 +472,7 @@ use
 useroutecard
 usesym
 value
+vdz
 version\n
 very
 verytightopt
 
@@ -31,3 +31,4 @@ MOPAC → spec) is the bridge it would reuse.
 - [Without `symops` every fragment column is empty and no line is drawn](empty-and-no-line-is-drawn.md)
 - [A fragment column is not sorted by energy](not-sorted-by-energy.md)
 - [Fragment columns may be opened out for legibility; the molecular column never is](fragment-columns-may-be-opened-out-for.md)
+- [MO composition: MoAoBasis, Mulliken by default (#161)](mo-composition-is-moaobasis-mulliken-by-default.md)
@@ -0,0 +1,28 @@
+---
+type: map
+title: "MO composition: MoAoBasis, Mulliken by default (#161)"
+area: mo-diagram
+section: "The MO correlation diagram (#132)"
+paths: ["include/tdat/MoAoBasis.H", "src/tdat/chemistry/MoAoBasis.C", "src/apps/mocomp/mocomp.C", "src/apps/builder/MoPanel.C", "tests/mocomp"]
+issues: [161, 132]
+---
+`MoAoBasis` (tdat, no wx) owns the walk that says what each MO coefficient
+column is: atom, l, nth shell of that l, component, and the real overlap
+matrix. `MoDiagramPanel`'s `functionsPerAtom()`/`buildBasisOverlap()` are thin
+wrappers on it, so the diagram, the MOs panel text, View Coeff's `%` column and
+`ecce-mocomp` cannot disagree about the basis.
+
+Default method is Mulliken `c_i (S c)_i / c.S.c` (the diagram's own share);
+`c^2` is the option. Mulliken parts are unbounded: do not threshold on them
+(that is what the Lowdin share in `MoComposition` is for).
+
+Checked against Multiwfn (Mulliken and Ros-Schuit) for ORCA water, benzene,
+CH3 (UHF), Cr(CO)6 and Gaussian 16 formaldehyde with Cartesian d: worst
+difference about 0.001 percentage point. `tests/mocomp/README.md` says how the
+fixtures and references were made. The fixtures are local-data calculation
+folders (`.ecce-meta`), not the data-server `.DAV` folders of `tests/modiagram`,
+which `ecce-mocomp` cannot open.
+
+Headless screenshots of the Builder need `ECCE_PANEL_MODE=classic`: in the
+default `detail` mode the molecule and the MOs pane did not appear in a
+private-Xvfb run, with or without this feature.