core dumped

[ishfaq333]

Hello there,
I was running the program unit-cell-creator.cpp
for
const int num_materials=2;
the results are good
but when I change the value form 2 to 1,
it shows core dumped:

terminate called after throwing an instance of 'std::out_of_range'
what(): vector::_M_range_check: __n (which is 1) >= this->size() (which is 1)
Aborted (core dumped)

Please help