These are the different types of models that psphot takes:

(these are located in psModules/src/objects/models)

psphot name	filename	function	comment
PS_MODEL_GAUSS	pmModel_GAUSS.c	exp(-z)	Pure gaussian
PS_MODEL_PGAUSS	pmModel_PGAUSS.c	1 / (1 + z + z2/2 + z3/6)	Gaussian taylor expansion
PS_MODEL_PS1_V1	pmModel_PS1_V1.c	1 / (1 + kz + z(3.33/2)) (z = r2, so r3.33)	power-law with fitted linear term
PS_MODEL_QGAUSS	pmModel_QGAUSS.c	1 / (1 + kz + z2.25)	power-law with fitted linear term
PS_MODEL_RGAUSS	pmModel_RGAUSS.c	1 / (1 + z + zalpha)	power-law with fitted slope
PS_MODEL_SERSIC	pmModel_SERSIC.c	f = exp(-zn)