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BohrSommerfeld model 2/2 https://en.wikipedia.org/wiki/BohrSommerfeld_model reference science, encyclopedia 2026-05-05T16:28:10.422419+00:00 kb-cron
            d
            
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          u
        
        
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            φ
            
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    =
    
    
      (
      
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                Z
                
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      (
      
        1
        +
        
          
            W
            
              
                m
                
                  
                    0
                  
                
              
              
                c
                
                  2
                
              
            
          
        
      
      )
    
    =
    
    
      ω
      
        
          0
        
      
      
        2
      
    
    u
    +
    K
  

{\displaystyle {\frac {d^{2}u}{d\varphi ^{2}}}=-\left(1-k^{2}{\frac {Z^{2}e^{4}}{c^{2}p_{\mathrm {\varphi } }^{2}}}\right)u+{\frac {m_{\mathrm {0} }kZe^{2}}{p_{\mathrm {\varphi } }^{2}}}\left(1+{\frac {W}{m_{\mathrm {0} }c^{2}}}\right)=-\omega _{\mathrm {0} }^{2}u+K}

with solution

    u
    =
    
      
        1
        r
      
    
    =
    K
    +
    A
    cos
    
    
      ω
      
        
          0
        
      
    
    φ
  

{\displaystyle u={\frac {1}{r}}=K+A\cos \omega _{\mathrm {0} }\varphi }

The angular shift of periapsis per revolution is given by

      φ
      
        
          s
        
      
    
    =
    2
    π
    
      (
      
        
          
            1
            
              ω
              
                
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        1
      
      )
    
    ≈
    4
    
      π
      
        3
      
    
    
      k
      
        2
      
    
    
      
        
          
            Z
            
              2
            
          
          
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            n
            
              
                φ
              
            
            
              2
            
          
          
            h
            
              2
            
          
        
      
    
  

{\displaystyle \varphi _{\mathrm {s} }=2\pi \left({\frac {1}{\omega _{\mathrm {0} }}}-1\right)\approx 4\pi ^{3}k^{2}{\frac {Z^{2}e^{4}}{c^{2}n_{\mathrm {\varphi } }^{2}h^{2}}}}

With the quantum conditions

    ∮
    
      p
      
        
          φ
        
      
    
    
    d
    φ
    =
    2
    π
    
      p
      
        
          φ
        
      
    
    =
    
      n
      
        
          φ
        
      
    
    h
  

{\displaystyle \oint p_{\mathrm {\varphi } }\,d\varphi =2\pi p_{\mathrm {\varphi } }=n_{\mathrm {\varphi } }h}

and

    ∮
    
      p
      
        
          r
        
      
    
    
    d
    r
    =
    
      p
      
        
          φ
        
      
    
    ∮
    
      
        (
        
          
            
              1
              r
            
          
          
            
              
                d
                r
              
              
                d
                φ
              
            
          
        
        )
      
      
        2
      
    
    
    d
    φ
    =
    
      n
      
        
          r
        
      
    
    h
  

{\displaystyle \oint p_{\mathrm {r} }\,dr=p_{\mathrm {\varphi } }\oint \left({\frac {1}{r}}{\frac {dr}{d\varphi }}\right)^{2}\,d\varphi =n_{\mathrm {r} }h}

we will obtain energies

        W
        
          
            m
            
              
                0
              
            
          
          
            c
            
              2
            
          
        
      
    
    =
    
      
        (
        
          1
          +
          
            
              
                
                  α
                  
                    2
                  
                
                
                  Z
                  
                    2
                  
                
              
              
                
                  (
                  
                    
                      n
                      
                        
                          r
                        
                      
                    
                    +
                    
                      
                        
                          n
                          
                            
                              φ
                            
                          
                          
                            2
                          
                        
                        
                        
                          α
                          
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                          Z
                          
                            2
                          
                        
                      
                    
                  
                  )
                
                
                  2
                
              
            
          
        
        )
      
      
        
        1
        
          /
        
        2
      
    
    
    1
  

{\displaystyle {\frac {W}{m_{\mathrm {0} }c^{2}}}=\left(1+{\frac {\alpha ^{2}Z^{2}}{\left(n_{\mathrm {r} }+{\sqrt {n_{\mathrm {\varphi } }^{2}-\alpha ^{2}Z^{2}}}\right)^{2}}}\right)^{-1/2}-1}

where

    α
  

{\displaystyle \alpha }

is the fine-structure constant. This solution (using substitutions for quantum numbers) is equivalent to the solution of the Dirac equation. Nevertheless, both solutions fail to predict the Lamb shifts.

== See also ==

Bohr model Old quantum theory

== References ==