Increasing the time step with mass scaling in Born‐Oppenheimer ab initio QM/MM molecular dynamics simulations |
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Authors: | Han Zheng Shenglong Wang Yingkai Zhang |
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Institution: | Department of Chemistry, New York University, New York, New York 10003 |
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Abstract: | Born‐Oppenheimer ab initio QM/MM molecular dynamics simulation with umbrella sampling is a state‐of‐the‐art approach to calculate free energy profiles of chemical reactions in complex systems. To further improve its computational efficiency, a mass‐scaling method with the increased time step in MD simulations has been explored and tested. It is found that by increasing the hydrogen mass to 10 amu, a time step of 3 fs can be employed in ab initio QM/MM MD simulations. In all our three test cases, including two solution reactions and one enzyme reaction, the resulted reaction free energy profiles with 3 fs time step and mass scaling are found to be in excellent agreement with the corresponding simulation results using 1 fs time step and the normal mass. These results indicate that for Born‐Oppenheimer ab initio QM/MM molecular dynamics simulations with umbrella sampling, the mass‐scaling method can significantly reduce its computational cost while has little effect on the calculated free energy profiles. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2009 |
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Keywords: | molecular dynamics simulation ab initio QM/MM method time step free energy profile umbrella sampling |
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