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This study aims to propose a contactless and continuous dielectrophoretic cell-separation device using quadrupole electric field. To examine the separation performance, numerical simulations of the electric field in the cross-section of the glass capillary installed in the center of the quadrupole electrode were conducted.

To estimate the magnitude of the dielectrophoretic force induced on cells, electrostatic analysis was performed by using a boundary-fitted coordinate system.Distribution of the electric field and gradient of the electric field square in the cross-section of the glass capillary were simulated for various ratios of radii of the glass capillary to the electrode rod.

The distribution of the electric field was found to have a cone-like profile about the center axis of the glass capillary with maximum at the internal surface of the glass capillary. The magnitude of the gradient of electric field square had similar distribution as that of the electric field, but had steeper slope near the internal surface of the glass capillary. The optimal values of the ratio of radii and the applied voltage were also estimated to achieve the local electric field strength suitable for cell separation.

One major advantage of the proposed device is simple and low fabrication cost, in addition to its contactless structure free from cell damage. Derived knowledge is instructive in achieving high-throughput cell separation without the use of devices of complex structure.

It has been well known that the quantum zero‐point energy (ZPE) cannot be conserved in simulations of atoms and molecules dynamics based on classical mechanics. The purpose of this paper is to examine fundamental issues related to the treatment of quantum ZPE constraint in simulations of atoms and molecules dynamics.

The ZPE is well known to be a quantum mechanical expectation value that is equivalent to an ensemble average when this value is interpreted to classical mechanics. An important point is that the ensemble‐averaged energies on simulations are expected to obey the ZPE criteria rather than those of individual simulation. The point is elucidated using quasiclassical trajectory calculations with a popular hydrogen atom‐diatom direct collision process incorporating a potential energy surface of a triatomic hydrogen system.

The results obtained by using standard classical trajectory calculations agree well with the quantum calculations. Using them, the author found that the classical results remain valid even if some trajectory calculations have vibrational energies that are less than the ZPE.

It is found that the ensemble‐average of each trajectory calculation can provide results that are consistent with quantum mechanical ones that obey the ZPE criteria, without the introduction of any additional constraint conditions for atoms and simulation algorithms.