[BUG] pt: fix torch.cat error in the C++ interface when nloc==0

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when a processor has no atoms, it throws the following errors:
terminate called after throwing an instance of 'c10::Error'
what(): torch.cat(): expected a non-empty list of Tensors
Exception raised from meta at /home/conda/feedstock_root/build_artifacts/libtorch_1706629241544/work/aten/src/ATen/native/TensorShape.cpp:256 (most recent call first):
frame #0: c10::Error::Error(c10::SourceLocation, std::__cxx11::basic_string<char, std::char_traits, std::allocator >) + 0xb2 (0x1456de6755d2 in /home/jz748/anaconda3/envs/dp3/bin/../lib/././libc10.so)
frame #1: c10::detail::torchCheckFail(char const*, char const*, unsigned int, char const*) + 0xfa (0x1456de62ad7c in /home/jz748/anaconda3/envs/dp3/bin/../lib/././libc10.so)
frame #2: at::meta::structured_cat::meta(c10::IListRefat::Tensor const&, long) + 0x9dc (0x1456485f6fdc in /home/jz748/anaconda3/envs/dp3/bin/../lib/././libtorch_cpu.so)
frame #3: + 0x2337b7d (0x145649337b7d in /home/jz748/anaconda3/envs/dp3/bin/../lib/././libtorch_cpu.so)
frame #4: + 0x2337c23 (0x145649337c23 in /home/jz748/anaconda3/envs/dp3/bin/../lib/././libtorch_cpu.so)
frame #5: at::_ops::cat::call(c10::IListRefat::Tensor const&, long) + 0x1af (0x145648a1e97f in /home/jz748/anaconda3/envs/dp3/bin/../lib/././libtorch_cpu.so)
frame #6: createNlistTensor(std::vector<std::vector<int, std::allocator >, std::allocator<std::vector<int, std::allocator > > > const&) + 0x405 (0x1456de7a0d65 in /home/jz748/anaconda3/envs/dp3/bin/../lib/./libdeepmd_cc.so)
frame #7: void deepmd::DeepPotPT::compute<double, std::vector<double, std::allocator > >(std::vector<double, std::allocator >&, std::vector<double, std::allocator >&, std::vector<double, std::allocator >&, std::vector<double, std::allocator >&, std::vector<double, std::allocator >&, std::vector<double, std::allocator > const&, std::vector<int, std::allocator > const&, std::vector<double, std::allocator > const&, int, deepmd::InputNlist const&, int const&, std::vector<double, std::allocator > const&, std::vector<double, std::allocator > const&) + 0x52c (0x1456de7a563c in /home/jz748/anaconda3/envs/dp3/bin/../lib/./libdeepmd_cc.so)
frame #8: void deepmd::DeepPotModelDevi::compute(std::vector<double, std::allocator >&, std::vector<std::vector<double, std::allocator >, std::allocator<std::vector<double, std::allocator > > >&, std::vector<std::vector<double, std::allocator >, std::allocator<std::vector<double, std::allocator > > >&, std::vector<std::vector<double, std::allocator >, std::allocator<std::vector<double, std::allocator > > >&, std::vector<std::vector<double, std::allocator >, std::allocator<std::vector<double, std::allocator > > >&, std::vector<double, std::allocator > const&, std::vector<int, std::allocator > const&, std::vector<double, std::allocator > const&, int, deepmd::InputNlist const&, int const&, std::vector<double, std::allocator > const&, std::vector<double, std::allocator > const&) + 0x367 (0x1456de799057 in /home/jz748/anaconda3/envs/dp3/bin/../lib/./libdeepmd_cc.so)
frame #9: void DP_DeepPotModelDeviComputeNList_variant(DP_DeepPotModelDevi*, int, int, double const*, int const*, double const*, int, DP_Nlist const*, int, double const*, double const*, double*, double*, double*, double*, double*) + 0x321 (0x1456f74126e1 in /home/jz748/anaconda3/envs/dp3/bin/../lib/libdeepmd_c.so)
frame #10: LAMMPS_NS::PairDeepMD::compute(int, int) + 0xf2f (0x1456e6c7d21f in /home/jz748/anaconda3/envs/dp3/lib/deepmd_lmp/dpplugin.so)
frame #11: LAMMPS_NS::Verlet::setup(int) + 0x3a2 (0x1456885c2552 in /home/jz748/anaconda3/envs/dp3/lib/python3.11/lib-dynload/../../liblammps.so)
frame #12: LAMMPS_NS::Run::command(int, char**) + 0xa1c (0x14568855969c in /home/jz748/anaconda3/envs/dp3/lib/python3.11/lib-dynload/../../liblammps.so)
frame #13: LAMMPS_NS::Input::execute_command() + 0x76a (0x1456883bb5ba in /home/jz748/anaconda3/envs/dp3/lib/python3.11/lib-dynload/../../liblammps.so)
frame #14: LAMMPS_NS::Input::one(std::__cxx11::basic_string<char, std::char_traits, std::allocator > const&) + 0x97 (0x1456883bc5c7 in /home/jz748/anaconda3/envs/dp3/lib/python3.11/lib-dynload/../../liblammps.so)
frame #15: lammps_command + 0x90 (0x145688408eb0 in /home/jz748/anaconda3/envs/dp3/lib/python3.11/lib-dynload/../../liblammps.so)
frame #16: + 0x6a4a (0x14571dfffa4a in /home/jz748/anaconda3/envs/dp3/lib/python3.11/lib-dynload/../../libffi.so.8)
frame #17: + 0x5fea (0x14571dffefea in /home/jz748/anaconda3/envs/dp3/lib/python3.11/lib-dynload/../../libffi.so.8)
frame #18: + 0x12545 (0x14570d2bf545 in /home/jz748/anaconda3/envs/dp3/lib/python3.11/lib-dynload/_ctypes.cpython-311-x86_64-linux-gnu.so)
frame #19: + 0x8802 (0x14570d2b5802 in /home/jz748/anaconda3/envs/dp3/lib/python3.11/lib-dynload/_ctypes.cpython-311-x86_64-linux-gnu.so)
frame #20: _PyObject_MakeTpCall + 0x253 (0x556477a31323 in /home/jz748/anaconda3/envs/dp3/bin/python3.11)
frame #21: _PyEval_EvalFrameDefault + 0x716 (0x556477a3ee36 in /home/jz748/anaconda3/envs/dp3/bin/python3.11)
frame #22: _PyFunction_Vectorcall + 0x181 (0x556477a624c1 in /home/jz748/anaconda3/envs/dp3/bin/python3.11)
frame #23: _PyEval_EvalFrameDefault + 0x49f9 (0x556477a43119 in /home/jz748/anaconda3/envs/dp3/bin/python3.11)
frame #24: + 0x2a442d (0x556477af542d in /home/jz748/anaconda3/envs/dp3/bin/python3.11)
frame #25: PyEval_EvalCode + 0x9f (0x556477af4abf in /home/jz748/anaconda3/envs/dp3/bin/python3.11)
frame #26: + 0x2c2a1a (0x556477b13a1a in /home/jz748/anaconda3/envs/dp3/bin/python3.11)
frame #27: + 0x2be593 (0x556477b0f593 in /home/jz748/anaconda3/envs/dp3/bin/python3.11)
frame #28: + 0x2d3930 (0x556477b24930 in /home/jz748/anaconda3/envs/dp3/bin/python3.11)
frame #29: _PyRun_SimpleFileObject + 0x1ae (0x556477b242ce in /home/jz748/anaconda3/envs/dp3/bin/python3.11)
frame #30: _PyRun_AnyFileObject + 0x44 (0x556477b23ff4 in /home/jz748/anaconda3/envs/dp3/bin/python3.11)
frame #31: Py_RunMain + 0x374 (0x556477b1e6f4 in /home/jz748/anaconda3/envs/dp3/bin/python3.11)
frame #32: Py_BytesMain + 0x37 (0x556477ae4a77 in /home/jz748/anaconda3/envs/dp3/bin/python3.11)
frame #33: + 0x27b8a (0x14571e136b8a in /lib64/libc.so.6)
frame #34: __libc_start_main + 0x8b (0x14571e136c4b in /lib64/libc.so.6)
frame #35: + 0x29391d (0x556477ae491d in /home/jz748/anaconda3/envs/dp3/bin/python3.11)

Line: 753

deepmd-kit//source/lmp/tests/test_lammps_pt.py

Lines 750 to 760 in fb61efb

	)
	def test_pair_deepmd_mpi(balance_args: list):
	if balance_args == []:
	# TODO: [BUG] pt: fix torch.cat error in the C++ interface when nloc==0
	# when a processor has no atoms, it throws the following errors:
	# terminate called after throwing an instance of 'c10::Error'
	# what(): torch.cat(): expected a non-empty list of Tensors
	# Exception raised from meta at /home/conda/feedstock_root/build_artifacts/libtorch_1706629241544/work/aten/src/ATen/native/TensorShape.cpp:256 (most recent call first):
	# frame #0: c10::Error::Error(c10::SourceLocation, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) + 0xb2 (0x1456de6755d2 in /home/jz748/anaconda3/envs/dp3/bin/../lib/././libc10.so)
	# frame #1: c10::detail::torchCheckFail(char const*, char const*, unsigned int, char const*) + 0xfa (0x1456de62ad7c in /home/jz748/anaconda3/envs/dp3/bin/../lib/././libc10.so)
	# frame #2: at::meta::structured_cat::meta(c10::IListRef<at::Tensor> const&, long) + 0x9dc (0x1456485f6fdc in /home/jz748/anaconda3/envs/dp3/bin/../lib/././libtorch_cpu.so)

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Closed in commit c2371cd