The Chemistry Maths Book, Second Edition

(Grace) #1

490 Chapter 17Determinants


This follows from the expansion of the three determinants along the relevant row or


column; column 1 in (17.43). Thus,



  1. Interchange of rows (or columns). Antisymmetry


If two rows (or two columns) of a determinant are interchanged the


value of the determinant is multiplied by (−1):


(17.44)


(17.45)


The determinant is said to be antisymmetricwith respect to the interchange of rows


or columns. It is this property of determinants that has made them so useful for the


construction of electronic wave functions.


EXAMPLE 17.11Determinant of order 2.


For interchange of columns,


ab


ab


ab ba ba ab


ba


ba


1
1

22

12 12 12 12

1
1

22

=−=− − =−()


abc


abc


abc


acb


acb


acb


1
11

222

333

1
11

222

333

=− (inter rchange of columns and23)


abc


abc


abc


abc


abc


abc


1
11

222

333

2
22

111

333

=− (inter rchange of rows and12)


=+


abc


abc


abc


dbc


dbc


dbc


1
11

222

333

1
11

222

333

+−+d


bc


bc


d


bc


bc


d


bc


bc


1

2
2

33

2

1
1

33

3

1
1

22

=−+a


bc


bc


a


bc


bc


a


bc


bc


1

2 2

33

2

1 1

33

3

1 1

22

ad b c


ad bc


ad bc


ad


bc


bc


11
11

2222

33 33

11

2
2

33













=+() −−+() ()ad ++


bc


bc


ad


bc


bc


22

1
1

33

33

1
1

22
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