align not producing same result as Chimera 1

[Eric Pettersen]

If you open 1b17 and 1ben (in that order) and then use this command:

[X]: mm #2/c to #1/a pair ss iter false
[1]: mm #0:.a #1:.c pair ss iter false

then ChimeraX produces a different RMSD than Chimera1 (X: 0.997; 1: 0.988) and the transforms differ:

X...
[[ 0.35290881 -0.92383834 -0.14825009 34.04070549]
[ 0.58233724 0.09285298 0.80762718 38.77041338]
[ -0.73235149 -0.3713503 0.57075411 22.1593799 ]]

1...
0.354798 -0.923616 -0.145094 34.0503
0.58081 0.0961279 0.808343 38.7099
-0.732651 -0.371071 0.570552 22.1571

The input atomic coordinates are identical (to at least the 5th decimal).

[Tom Goddard]

Eric reports that the problem is that the mmcif and pdb format coordinates are different in ChimeraX and using PDB format files in ChimeraX and Chimera 1 gives the same match maker result.