srp potential with gcmc

Hello LAMMPS users,

Using the srp potential with fix gcmc I run into some issues. If I remove the srp potential my simulations run fine. When I include fix srp the simulations become many orders of magnitude slower. I included simplified test scripts which can be ran to reproduce the issue. The only difference between the two scripts is the srp bond potential, which should invoke the full_energy option in gcmc. Is the reason for the drastic drop in performance really due to the full_energy option being invoked or is it due to something else.

I ran the code in GDB and after it got stuck I stopped the run (control + C) and looked at the stack trace.

Program received signal SIGINT, Interrupt.
0x000000000065d7d5 in LAMMPS_NS::FixGCMC::energy_full (this=0xf7cfd0) at …/fix_gcmc.cpp:2285
2285 if (rsq < overlap_cutoffsq) {
Missing separate debuginfos, use: debuginfo-install fftw-3.2.1-3.1.el6.x86_64 glibc-2.12-1.166.el6_7.3.x86_64 libgcc-4.4.7-18.el6.x86_64 libjpeg-turbo-1.2.1-3.el6_5.x86_64 libstdc+±4.4.7-18.el6.x86_64
(gdb) where
#0 0x000000000065d7d5 in LAMMPS_NS::FixGCMC::energy_full (this=0xf7cfd0) at …/fix_gcmc.cpp:2285
#1 0x0000000000659c93 in LAMMPS_NS::FixGCMC::attempt_atomic_insertion_full (this=0xf7cfd0) at …/fix_gcmc.cpp:1698
#2 0x000000000065373f in LAMMPS_NS::FixGCMC::pre_exchange (this=0xf7cfd0) at …/fix_gcmc.cpp:779
#3 0x00000000007a245f in LAMMPS_NS::Modify::pre_exchange (this=0xf6faf0) at …/modify.cpp:408
#4 0x0000000000afd131 in LAMMPS_NS::Verlet::run (this=0xf76b90, n=500000) at …/verlet.cpp:267
#5 0x0000000000ab9c85 in LAMMPS_NS::Run::command (this=0x7fffffffdf90, narg=1, arg=0xf7ae70) at …/run.cpp:183
#6 0x0000000000769063 in LAMMPS_NS::Input::command_creator<LAMMPS_NS::Run> (lmp=0xf5b010, narg=1, arg=0xf7ae70) at …/input.cpp:863
#7 0x00000000007630ec in LAMMPS_NS::Input::execute_command (this=0xf5b960) at …/input.cpp:846
#8 0x00000000007608d1 in LAMMPS_NS::Input::file (this=0xf5b960) at …/input.cpp:243
#9 0x000000000077d7e9 in main (argc=3, argv=0x7fffffffe258) at …/main.cpp:64



no_srp.mem (1.85 KB)

srp.mem (2.12 KB)

New.dat (3.34 KB)

Forgot to mention, I am running the latest stable lammps version (lammps-16Mar18) with the USER-MISC, MISC, and MC packages installed.

I’m CCing Tim Sirk who can comment on issues with fix srp.
I don’t know if using it with fix gcmc is problematic or not.