<div>Dear all,</div>
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<div>I've run this simulation twice, but got exactly the same error. Everything was fine up to position restrained simulation. However, the MD simulation was not successful. The final error is:</div>
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<div>-------------------------------------------------------<br>Program mdrun, VERSION 3.3.2<br>Source code file: nsgrid.c, line: 220</div>
<div>Fatal error:<br>Number of grid cells is zero. Probably the system and box collapsed.</div>
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<div>Starting from step 1749465 (3498.93 ps), more and more bonds that rotated more than 30 degrees appeared. Starting from step 1749466, the warning "pressure scaling more than 1%, mu: 1.27191e+06 1.27191e+06 1.27191e+06" started to appear, and the system collapsed at step 1749467.</div>
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<div>Does anyone have idea what might be wrong? I was simulating a calcium-binding protein with calcium atoms in water for 4ns. Thanks!</div>
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<div>Peggy</div>