The growth of dust particles into planet embryos needs to circumvent the “ radial-drift barrier ” , i.e . the accretion of dust particles onto the central star by radial migration .
The outcome of the dust radial migration is governed by simple criteria between the dust-to-gas ratio and the exponents p and q of the surface density and temperature power laws .
The transfer of radiation provides an additional constraint between these quantities because the disc thermal structure is fixed by the dust spatial distribution .
To assess which discs are primarily affected by the radial-drift barrier , we used the radiative transfer code MCFOST to compute the temperature structure of a wide range of disc models , stressing the particular effects of grain size distributions and vertical settling .

We find that the outcome of the dust migration process is very sensitive to the physical conditions within the disc .
For high dust-to-gas ratios ( \gtrsim 0.01 ) and/or flattened disc structures ( H / R \lesssim 0.05 ) , growing dust grains can efficiently decouple from the gas , leading to a high concentration of grains at a critical radius of a few AU .
Decoupling of grains from gas can occur at a large fraction ( > 0.1 ) of the initial radius of the particle , for a dust-to-gas ratio greater than \approx 0.05 .
Dust grains that experience migration without significant growth ( millimetre and centimetre-sized ) are efficiently accreted for discs with flat surface density profiles ( p < 0.7 ) while they always remain in the disc if the surface density is steep enough ( p > 1.2 ) .
Between ( 0.7 < p < 1.2 ) , both behaviours may occur depending on the exact density and temperature structures of the disc .
Both the presence of large grains and vertical settling tend to favour the accretion of non-growing dust grains onto the central object , but it slows down the migration of growing dust grains .
If the disc has evolved into a self-shadowed structure , the required dust-to-gas ratio for dust grains to stop their migration at large radius become much smaller , of the order of 0.01 .
All the disc configurations are found to have favourable temperature profiles over most of the disc to retain their planetesimals .