[SIESTA-L] underestimated zone center frequencies in MgO ?

Sat, 06 Mar 2010 08:46:47 -0800 

Hi dear all Siesta Users,
                 i tried to reproduce the zone center frequencies in MgO.
But they are not same as  shown in JOURNAL OF APPLIED PHYSICS 100,
023533,2006. In this paper, doubly degenerate freq is ~400 cm-1 and other is
~700cm-1 apart from acoustical freqs.

But Siesta calculates following freqs :

  eigenvalue #           1  omega= -5.342383622781044E-002
  eigenvalue #           2  omega=  9.129011837545617E-003
  eigenvalue #           3  omega=  4.213637115974628E-002
  eigenvalue #           4  omega=   397.442968241599
  eigenvalue #           5  omega=   413.630587428353
  eigenvalue #           6  omega=   413.916231936010

I used the basis and pp for  MgO as used by J. Junquera et al., Phys. Rev.
B, 64, 235111 (2001), available on siesta site.

I am wondering, How can i reproduce them? i am attaching the input file.

I need your help to reproduce the correct frequencies.

With due Regards,

Sonu Kumar

Phd Student
Indian Institute of Technology Delhi
Delhi-110016
web:-http://www.iitd.ac.in/

Attachment: mgo.fdf
Description: application/vnd.fdf

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