MDLJSP2 MDLDP2 1 GENERAL 1.1 Description MDLJSP2 (single precision version) MDLJDP2 (double precision version) These programs solve the equations of motion for a model of 500 atoms interacting through the idealized Lennard-Jones potential. This would be a typical system used to model the structure of (say) liquid Argon. At each time step in the calculation, the positions and velocities of each particle in the model system are used to calculate the configurational energy and pressure through the equations of statistical mechanics. These properties can be directly compared with experimental measurements, which gives some idea of the quality of the interatomic potential used (Lennard-Jones in this case). The density and temperature for the model is supplied through an input file. One difficulty of comparing theoretical calculations with experimental measurements is the uncertainty in the interatomic potentials, which in general are not known for real systems. However, Molecular Dynamics calculations provide essentially exact results for a given model interatomic potential, and so provide a source of 'experimental' data with which theory can be compared free of uncertanties in the potential. 1.3 Source/Author Steve Thompson School of Chemical Engineering Cornell University Ithaca NY 14853 1.3 Version/Date 1.4 Classification FORTRAN floating point scientific benchmark. Two versions are available - a single precision version and a double precision version. 1.5 Application Category Quantum Chemistry 1.6 Justification - Added Value to Current Release MDLJSP2 and MDLJDP2 alow overhead compariosn of double and single precision floating point performance. No other set of SPEC benchmarks allow for this comparion. The two benchmarks add a quantum chemistry benchmark to the family of applications already presented. 1.7 Other Information This original version of this benchmark has been run by Cornell on a variety of workstations and high performance computing systems. 2 PERFORMANCE 2.1 Metrics Elapsed time to complete the execution of benchmark program. 2.2 Elapsed Time ( reference ) The SPEC refereence time for 034.mdljdp2 (to 3 sig. fig) is 7090 seconds. The SPEC refereence time for 077.mdljsp2 (to 3 sig. fig) is 3350 seconds. 2.3 Reports Writes a small output file (unit 6) for comparison with reference. 2.4 Additional Performance Considerations None. 3 SOFTWARE 3.1 Language Fortran. 3.2 Operating System This benchmark has been ported easily to several different operating systems. It has no known OS dependencies. 3.3 Portability Easy to port. 3.4 Vectorizability/Multiprocessor Issues Amenable to vectorization and decomposition on systems that provide such capabilities. 3.5 Miscellaneous Software None. 3.6 Known Bugs None. 3.7 Additional Software Considerations For 64bit systems, some source modules are replaced. This is done to keep the calculations 64 bit oriented as opposed to having them be promoted to quadruple precision (128 bits). This is an issue for CDC and other systems and that change was done for benchmark fairness. 3.8 Benchmark History Benchmark codes derived from production version used at Cornell University for Chemical Engineering research. Changes for SPEC affect the format of the output but the primary calculations are as in the original. Changes for SPEC include: - Reformatted output to facilitate mechanical verification - Increased number of timesteps to increase benchmark runtime 4 HARDWARE 4.1 Memory No special requirements. 4.2 Disks No special requirements. 4.3 Communication None. 4.4 Special Hardware This benchmark contains floating point arithmetic. A single and a double precision version are available (MDLJSP2 and MDLJDP2). 4.5 Additional Hardware Considerations none 4.6 OPERATIONAL 4.7 Disk Space Source code and output files are small (.lt. 60kb) 4.8 Installation No special installation required. 4.9 Execution Image is compiled, Linked and Run. There are no Input files and a single (small) output file (unit 6) is produced. 4.10 Correctness Verification See output from sample run. 4.11 Additional Operational Considerations None. 4.12 Sample Build and Run Output produced by MDLJDP2: The files are: MDLJ2.DAT input data file; the programs prompt for this. MDLJSP2.F Source code for MDLJSP2 MDLJSP2.CMN Include file used by MDLJSP2.F MDLJDP2.F Source code for MDLJDP2 MDLJDP2.CMN Include file used by MDLJDP2.F Under VAX/VMS, these are compiled and linked with: $ FORTRAN MDLJSP2.f,MDLJDP2.f $ LINK MDLJSP2 $ LINK MDLJDP2 Name of input parameters file? MDLJDP2: MOLECULAR DYNAMICS BULK SIMULATION FOR 500 LENNARD-JONES ATOMS Desired Temperature 0.7000 (Reduced) Reduced Density 0.7900 Potential Truncation Distance 2.5000 Sigma Outer List Radius 2.7000 Sigma PLIST_UPDATE 0.8000 Reduced Time Step 0.00400 ************************ AVERAGES OVER 1000 STEPS ************************ Reduced Temperature 0.70 Mean Configurational Energy -2476.3 Total Energy -1952.9 *** END OF RUN AT STEP 1000 AFTER 2000 STEPS ***