**The meaning of overlap matrix position/momentum operator** |
- Date: 2024/04/11 18:16
- Name:
**Liang Liu**
<liangliu@mail.sdu.edu.cn>
- Hello! I have obtained the outputs from analysis_example and *.scfout from the calculations on H2 molecular. Each hydrogen has one s-PAO. I'm puzzled by the following sections:
Overlap matrix with position operator x global index=1 local index=0 (global=1, Rn=0 [0 0 0]) -1.580512401E-06 global index=1 local index=1 (global=2, Rn=0 [0 0 0]) 5.181934010E-01 global index=2 local index=0 (global=2, Rn=0 [0 0 0]) 1.580512401E-06 global index=2 local index=1 (global=1, Rn=0 [0 0 0]) -5.181934010E-01
I guess "Overlap matrix with position operator x" is: <s1| x |s2>, where s1, s2 are the s-PAOs, and the diagonal element should correspond to the atom coordinate. However, the diagonals from outputs = +/-1.58E-06 are not like any type of coordinate since the bond length of H2 is 0.74 angstrom and the molecular is placed in a box with size of 10 angstrom. Am I missing somethings?
On the other hand, the "Overlap matrix with momentum operator px" also bothers me:
Overlap matrix with momentum operator px global index=1 local index=0 (global=1, Rn=0 [0 0 0]) 9.051099278E-06 global index=1 local index=1 (global=2, Rn=0 [0 0 0]) -2.891951944E-01 global index=2 local index=0 (global=2, Rn=0 [0 0 0]) -9.051099278E-06 global index=2 local index=1 (global=1, Rn=0 [0 0 0]) 2.891951944E-01
It shows that the diagonals of <s1| px |s2> are not zero but how can the localized PAOs display finite expectations of momentum. Or all of my thinking are wrong?
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