Enhancement Factors for Positron Annihilation on Valence . . .
251
10
-5
10
-4
10
-3
10
-2
10
-1
10
0
10
1
10
2
|A(P)|
2
He 1s
10
-7
10
-6
10
-5
10
-4
10
-3
10
-2
10
-1
10
0
10
1
10
2
|A(P)|
2
Ar 3p
10
-5
10
-4
10
-3
10
-2
10
-1
10
0
10
1
|A(P)|
2
Ne 2p
10
-7
10
-6
10
-5
10
-4
10
-3
10
-2
10
-1
10
0
10
1
10
2
|A(P)|
2
Ar 3s
10
-5
10
-4
10
-3
10
-2
10
-1
10
0
10
1
|A(P)|
2
Ne 2s
10
-7
10
-6
10
-5
10
-4
10
-3
10
-2
10
-1
10
0
10
1
10
2
|A(P)|
2
Ar 2p
P (a.u.)
10
-5
10
-4
10
-3
10
-2
10
-1
10
0
10
1
|A(P)|
2
Ne 1s
0
1
2
3
4
5
6
0
1
2
3
4
5
6
P (a.u.)
10
-7
10
-6
10
-5
10
-4
10
-3
10
-2
10
-1
10
0
10
1
10
2
|A(P)|
2
Ar 2s
Fig. 3 Annihilation momentum density as a function of the total 2𝛾 momentum P, for s-wave
positron annihilation in He, Ne and Ar, calculated in different approximations for the annihilation
vertex: zeroth-order vertex (dashed lines); full vertex (0 + 1 + 𝛤 ) (solid lines), for HF (thin blue
lines) and Dyson (thick red lines) positron of momentum k = 0.04 a.u. (For a given approximation
for the vertex, the lines for the calculation with Dyson positron lie above those for HF positron)