7.4. Behavior of greenr2k utility

This utility is used as follows:

$ ${PATH}/greenr2k ${NAMELIST} ${GEOMETRY}

where ${PATH} is the path to the directory where the executable fourier exists, ${NAMELIST} is the NameList input-file name of HPhi++/mVMC, and ${GEOMETRY} is the path to the Geometry file.

The behavior of this utility is slightly different between the correlation functions from each mode of HPhi++ (Lanczos, TPQ, Full diagonalization, LOBCG) and mVMC. In the following cases, we assume that CDataFileHead in the ModPara input file is "zvo" (default).

7.4.1. HPhi-Lanczos

In this case, HPhi writes correlation functions to the files zvo_cisajs.dat (one body) and zvo_cisajscktalt.dat (two body) in output/ directory. fourier utility reads this files, performs the Fourier transformation, and generate single file zvo_corr.dat in output/ directory.

7.4.2. HPhi-TPQ

HPhi writes correlation functions to files zvo_cisajs_run*step*.dat (one body), zvo_cisajscktalt_run*step*.dat (two body) at each trial and TPQ step to the output/ directory. fourier utility reads the one- and the two-body correlation function at each trial/TPQ-step, and performs Fourier transformation, and write to a file zvo_corr_run*step*.dat in output/ directory.

7.4.3. HPhi-Full diagonalization and LOBCG

HPhi writes correlation functions to files zvo_cisajs_eigen*.dat (one body) and zvo_cisajscktalt_eigen*.dat (two body) for each wavefunction to the output/ directory. fourier utility reads the one- and the two-body correlation function at each state and performs Fourier transformation, and write to a file zvo_corr_eigen*.dat in output/.

7.4.4. mVMC

vmc.out performs calculations according to the input parameters NDataIdxStart and NDataQtySmp in ModPara file, and it generates zvo_cisajs_???.dat (one body) and zvo_cisajscktalt_???.dat (two body) in output/ directory. fourier utility reads all of these files, performs Fourier transformation, computes the average

\[\begin{align} \langle A \rangle = \frac{1}{N_{\rm Try}} \sum_{i=1}^{N_{\rm Try}} A_i \end{align}\]

and the standard error

\[\begin{align} \delta A = \frac{1}{N_{\rm Try} - 1} \sqrt{\frac{1}{N_{\rm Try}} \sum_{i=1}^{N_{\rm Try}} (A_i - \langle A \rangle)^2} \end{align}\]

of the real- and imaginary-part of each correlation function, and writes them to a file zvo_corr_eigen*.dat in output/ directory.