Madelung constant

  • Thread starter Petar Mali
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  • #1
Petar Mali
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Homework Statement


Applying the method of Evjen calculate Madelungovu constant of infinitely long series of alternately opposite charged ions. Show that summarize by the Evjen cells gives the value Madelung constant [tex]A_n[/tex] whose deviation from actual value [tex]A[/tex] is less than [tex]\frac{1}{n^2}[/tex]


Homework Equations


Madelung constant Madelung constant for the infinite number of ions alternately changing signs

[tex]A=2(1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+...)=2ln2[/tex]



The Attempt at a Solution


Evjen method is method in which we look in neutral structures. So I think that first neutral structure is one whole ion and two neighbours cut in half. And second neutral structure is all other ions. Is it than Madelung constant for first neutral structure

[tex](A)_I=2\cdot 0,5=1[/tex]

and for second neutral structure

[tex](A)_{II}=2(0,5-\frac{1}{2}+\frac{1}{3}-...)[/tex]

And

[tex]A_n=(A)_I+(A)_{II}[/tex]

But where I have [tex]n[/tex] in here?

Homework Statement





Homework Equations





The Attempt at a Solution

 

Answers and Replies

  • #2
Petar Mali
290
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Any idea?
 

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