shake comparison

From: Xiaoliang Qian <>
Date: Fri 23 Feb 2001 12:13:07 -0500

Hi, everyone.

I have a question about the shake schemes in Charmm and AMBER.
I found two shake schemes exist

X0: coordinate at t0,
X1: coordinate at t0+dt, before shake correction
X2: coordinate at t0+dt, after shake correction
V0: velocity at t0;
V1: velocity at t0+dt, with shake correction;

V1=(X2-X0)/dt -------------------- scheme I
V1=V0+(X2-X1)/dt ------------------ scheme II

Scheme I is used for single time step integrator
both in Charmm and AMBER.

Scheme II is used for multi-time step integrator in Charmm.

Can anyone explain to me why different shake schemes are used?

Received on Fri Feb 23 2001 - 09:13:07 PST
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