"The molecular dynamics problem is generally treated as a coupled set of differential equations. The system of differential equation is discretized by choosing a discrete time step. Given the position and velocity of each particle at one time step, molecular dynamics simulation algorithms estimate these values at the next time step."
"The Time step is a crucial parameter in MD simulations as it determines the accuracy and efficiency of the numerical integration scheme. By default, the time step is typically set to 1 fs or less (in Q-Chem, 1 a.u. which is 0.0242 fs) in a number of codes.
"The central point is that a larger time step, although it may at first glance improve the efficiency of the simulation, increases the error in the numerical integration scheme of the equations of motion. The underlying assumption that the atomic forces are approximately constant during one integration step is not valid any more. Essentially, the chosen time step should be small enough to resolve the highest vibrational frequencies of the atoms (i.e. it should be much smaller than the smallest vibrational period), so if you have light atoms (e.g. hydrogen), you will generally be required to use a smaller time step than if you have only heavy atoms (such as gold). A smaller time step size may also be necessary if you have different elements in your calculation, if the temperature is high, or if the atoms are far away from their equilibrium configuration, i.e if large forces act on the particles. For most systems a safe choice to start, if you do not know what time step to use, is 1 fs. Larger timestep values can then be assessed by monitoring the conservation of the total energy in an NVE simulation under the conditions of interest."
To read more:
Molecular Dynamics: Basics (from quantumwise.com)
MD Molecular dynamics (a C program to do molecular dynamics
"The Time step is a crucial parameter in MD simulations as it determines the accuracy and efficiency of the numerical integration scheme. By default, the time step is typically set to 1 fs or less (in Q-Chem, 1 a.u. which is 0.0242 fs) in a number of codes.
"The central point is that a larger time step, although it may at first glance improve the efficiency of the simulation, increases the error in the numerical integration scheme of the equations of motion. The underlying assumption that the atomic forces are approximately constant during one integration step is not valid any more. Essentially, the chosen time step should be small enough to resolve the highest vibrational frequencies of the atoms (i.e. it should be much smaller than the smallest vibrational period), so if you have light atoms (e.g. hydrogen), you will generally be required to use a smaller time step than if you have only heavy atoms (such as gold). A smaller time step size may also be necessary if you have different elements in your calculation, if the temperature is high, or if the atoms are far away from their equilibrium configuration, i.e if large forces act on the particles. For most systems a safe choice to start, if you do not know what time step to use, is 1 fs. Larger timestep values can then be assessed by monitoring the conservation of the total energy in an NVE simulation under the conditions of interest."
To read more:
Molecular Dynamics: Basics (from quantumwise.com)
MD Molecular dynamics (a C program to do molecular dynamics
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