The author introduces boundary conditions for Dirac operators giving selfadjoint extensions such that the Hamiltonians define elliptic operators. Using finite propagation speed methods and assuming bounded geometry he estimates the trace of the difference of two heat operators associated to a pair of Dirac operators coinciding on cocompact sets.
@article{701512,
title = {Comparison of Dirac operators on manifolds with},
booktitle = {Proceedings of the Winter School "Geometry and Physics"},
series = {GDML\_Books},
publisher = {Circolo Matematico di Palermo},
address = {Palermo},
year = {1993},
pages = {[133]-141},
mrnumber = {MR1246627},
zbl = {0797.58084},
url = {http://dml.mathdoc.fr/item/701512}
}
Bunke, Ulrich. Comparison of Dirac operators on manifolds with, dans Proceedings of the Winter School "Geometry and Physics", GDML_Books, (1993), pp. [133]-141. http://gdmltest.u-ga.fr/item/701512/