[Re:02] Step-wise shift of total energy along with lattice constants

Posted on : February 16, 2017 (Thu) 20:42:58

by Administrator

It is crucial to keep the condition of the calculation during the series of runs to avoid such jumps that may happen when continuously changing the lattice constant. In most cases the calculational condition changes when the number of the real space lattice vectors and that of the reciprocal space vectors, which are used for generating structural Green's function, change. These number can be seen from the output:

last= 243 np= 15 nt= 331 nrpt= 177 nk= 554 nd= 1

In this case, 331 G-vectors and 177 R-vectors are used. These numbers depends on the lattice constant as well as the energy range specifies by input parameter 'ewidth'.
To keep these values unchanged, you have to fix the value of some control parameters:
Look into the program 'spmain.f'. At lines # 277 and 278 (if you are using the latest version of cpa2002v009c), you will find lines that seem like

275 c------- fix ew and ez to some special values
276 c write(*,'(1x,a)')' Fixed ew and ez are used'
277 c ew=-0.45563
278 c ez=1.2
279 c---------------------------------------

You may uncomment the lines from 276 through 278, giving some values to ew and ez. You have to choose the values from a typical calculations of your system. In the output, you will find the values for 'ew' and 'ez' that were used in that calculation. If you specify those values at these lines, the program is forced to use them for ew and ez. Try this and see. Does the total energy still jump? Never forget to comment them out when you use the code for usual ways.

KKR administrator