CASINO and computers

QMC calculations can be very computationally demanding. The demand varies according to the system and the statistical accuracy required: atomic calculations typically require only a few minutes on a PC, whereas calculating the excitonic properties of complex crystalline solids may require a great many CPU hours of supercomputer time.

QMC exhibits a high degree of scalability: demands on memory and disk are normally low, compared with high-order quantum chemistry methods. It is relatively easy to obtain c.100% parallel efficiency on a machine with hundreds of thousands and probably even millions of processors. CASINO has been mounted on many computers including machines in the Cambridge High-Performance Computing Centre and the UK national parallel facilities at Daresbury and Manchester. Internationally, it has been installed on some of the most powerful machines in the world such as JaguarPF, a Cray XK6 with 299008 cores at ORNL. The largest known calculations were run by Mike Towler on 124416 cores of JaguarPF and on 131072 cores of an IBM Blue Gene/P (Intrepid).

We are always grateful to be sent test timings and other relevant data for machines that we may not have access to.

The code has been tested and run on the following hardware (some of which may now have become obsolete):

Single-processor machines : (MPI library not required)

• Linux PCs (with Intel ifc/Intel ifort /Lahey lf95/NAG f95/Portland pgf90/GNU g95 compilers).
• Macs with the g95 compiler
• DEC Alpha
• SGI Octane

• Blue Gene/P, Blue Gene/Q
• Cray XT4, XT5, XT6, XK6
• SGI Origin 2000/3000
• SGI Altix (Itanium2)
• IBM SP3
• IBM P-series
• Fujitsu Primepower
• SunFire Galaxy
• Opteron clusters
• Alpha multiprocessors
• Linux multiprocessors and clusters (with above compilers)
• Cray T3E
• Hitachi SR2201