In this work, we investigate the thermal conductivity properties of
Si
1
−
x
Ge
x
and
Si
0.8
Ge
0
Sn
2
y
alloys. The equilibrium molecular dynamics (EMD) is employed to calculate the thermal conductivities of
Si
1
−
x
Ge
x
alloys when
x
is different at temperatures ranging from 100 K to 1100 K. Then nonequilibrium molecular dynamics (NEMD) is used to study the relationships between
y
and the thermal conductivities of
Si
0.8
Ge
0.2
Sn
2
y
alloys. In this paper, Ge atoms are randomly doped, and tin atoms are doped in three distributing ways: random doping, complete doping, and bridge doping. The results show that the thermal conductivities of
Si
1
−
x
Ge
x
alloys decrease first, then increase with the rise of
x
, and reach the lowest value when
x
changes from 0.4 to 0.5. No matter what the value of
x
is, the thermal conductivities of
Si
1
−
x
Ge
x
alloys decrease with the increase of temperature. Thermal conductivities of
Si
0.8
Ge
0.2
alloys can be significantly inhibited by doping an appropriate number of Sn atoms. For the random doping model, thermal conductivities of
Si
0.8
Ge
0.2
Sn
y
alloys approach the lowest level when
y
is 0.10. Whether it is complete doping or bridge doping, thermal conductivities decrease with the increase of the number of doped layers. In addition, in the bridge doping model, both the number of Sn atoms in the [001] direction and the penetration distance of Sn atoms strongly influence thermal conductivities. The thermal conductivities of
Si
0.8
Ge
0.2
Sn
y
alloys are positively associated with the number of Sn atoms in the [001] direction and the penetration distance of Sn atoms.
Accurate thermal conductivities from optimally short molecular dynamics simulations
