[Pw_forum] Clarification of celldm(4) in monoclinic

[Ridwan Agbaoye]

I am very grateful Prof. Giovanni Cantele, you have saved me a lot of stress 
Of course cos(ab) was defined in PW.html within A,B,C cos(ab) but not defined in among celldm(1)-celldm(6)
Many Thanks to all forum members  

    On Monday, December 21, 2015 5:27 AM, Giovanni Cantele <giovanni.cantele at spin.cnr.it> wrote:
 

 cos(ab) means cosine of the angle between lattice AXIS a and lattice AXIS b, so xcrysden gives you the correct view
see also Doc/INPUT_PW.txt at the description of the variable A, B, C, cosAB, cosAC, cosBC
Giovanni

On 21 Dec 2015, at 12:16, Ridwan Agbaoye <agbaoyeridwan at yahoo.com> wrote:
Good day everyone I need some help with clarification on celldm(4)=cos(ab) 
Does cos(ab) mean the cosine of angle between lattice parameter a and b or it means the cosine of the product of the lattice parameter a and b that is cosine(lattice parameter a*lattice parameter b)
when i view my input file using xcrysden it looks like a cubic structure when i used celldm(4)=cos(ab)=0 since angle between a and b is 90 degree
but looked like a monoclinic structure when i used cosine(lattice parameter a*lattice parameter b)
Am i getting the cos(ab) wrong
Many Thanks to everyone on this forum 
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