NuShellX shares the
same modular design as NuShell. The transition operator program
NuTra can take any combination of the operators I , N, a+, a-,
a+a-, a+a+ and a-a- for the neutrons and protons giving a total of about
22 useful possibilties. On of these 22 (a+a- x a+a-) is
used by the Lanczos routines. The combinations (a+ x a+a+ and a+a+ x
a+a+) give 3 particle and alpha transfer spectroscopic factors. These are
unique to NuShellX (and NuShell). The programs NuTrx and NuClx convert the
output of NuTra to decay rates and spectroscopic amplitudes
On a 3GHz Xeon Duo with
4GB of memory the release version will diagonalise the 0+ of 56Ni in
full fp-shell, dimension 15,443,684, in 19 hours. But note that the
code only requires 1.3GB of memory plus system overhead for this
case. But for full fp-shell calculations for 48Cr, the maximum time
to diagonalize any matrix is about 19 mins for J=6, dimension 226,259,
while the 0+, dimension 41,355, will take 38 seconds which is about 9
times faster than NuShell. For 48Cr the memory requirements are
minimal. When N/=Z much faster times will be possible. All the
above times are for the thick restart Lanczos method and 10 converged
eigenvalues.
NushellX will
be probably 5.5 and 10 times faster than published times for
Antoine (Strasbourg group m-scheme cousin of Nathan) for 0+ states in
56Ni and 52Fe correcting for processor differences. But in absolute terms
it will be 16.8 and 30 times faster on the Xeon Duo for 0+
states in 56Ni and 52Fe. A calculation that took 14 hours and 60GB memory
with Nushell has been done in less than 3 mins with 2GB memory with a
pre-release version of NuShellX on the same machine. This is nearly 300
times faster. Note however that for small calculations NuShell will
be faster than NuShellX and isospin can be used with NuShell but not with
NuShellX. But the isospin of final states is easily and quickly calculated.
For larger calculations
4 or more processors are recommended to speed up the calculations, but the
memory requirement also increases with the number of processors since each
processor must have its own copy of the new Lanczos vector and its
own buffers for intermediate storage. A large processor cache is also
advantageous as is a 10,000 RPM disk.
Note that the
diagonalisation of the Hamiltonian matrix has undergone extensive testing for
some aspects particularly stability. The transition rate codes have not had
extensive testing.
Many very useful and
helpful email exchanges with Jussi Toivanen are acknowledged.