Microchip claims that the models are made for PSPICE.
Both ngspice and LTSPICE fail with the MCP6001.
MCP6041 is o.k. with both.
MCP6561 again fails.
some editing of the model is required:
R61 0 61 100 TC 3.11M 4.51U
will become
R61 0 61 100 TC1=3.11M TC2=4.51U
.MODEL REXP RES TCE=10.1
will become
.MODEL REXP R TCE=10.1
But still no convergence.